Texured Metal Shaders For Industrial Design

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Textured Metal Shaders for Industrial Design:

UV-unwrapping - material nesting - displacement mapping - displacement mixing


by: Claas Eicke Kuhnen

Содержание

Introduction

This tutorial will explain how different types of metal surfaces, found in Industrial Design and Metal Art, can be rebuilt in Blender. It will cover brushed and hammered metal textures including modeling, UV-unwrapping, and texturing approaches and techniques.


Most of the scenes are jewelry related because this is my main field at the moment. However, everything explained can easily be transferred to any other type of object as well - as the last chapter shows.


1 Brushed metal shader:

Let's talk about a brushed metal shader first.


Many first semester students marvel about their first casted silver ring after they've started to clean up their first casting with sand paper. They love to move the ring around and enjoy watching the change of those stretched highlights. But what are those anisotropic reflections? Micro fine grooves inside a polished metal surface reflect the incoming light at different angles away - perpendicular to the grooves direction.


Those visual elements, most commonly known as linear and circular brush patterns, are called anisotropic specular reflections, or short anisotropic highlights. However, those grooves also spread the reflection value in the same manner. This is known as anisotropic reflection. It is not just a diffused, radial blurred reflection, because the anisotropic reflection is stretched as the specular highlight reflection is stretched. An anisotropic reflection is composed out of many fine parallel reflection lines, depending on the groove size.


It is important to know that close objects appear more clear in the reflection and far objects appear more diffused. The last point is especially what is currently difficult to recreate with the Blender material system. It is not only a question of stretching a reflection along one axis perpendicular to micro-fine grooves, but furthermore to make that reflection have the correct blurriness according to the distance between the reflected and the reflecting surface.


To create this visual effect we need to create a bump map which can provide us with the needed amount of fine grooves. Because we work in 72 DPI and not the real world, we only have a limited amount of visual information (pixels) to create this effect. The solution to this technical problem is to create a blend of different materials which all have slightly different bump values. By overlaying and mixing them together we can create that fine surface we need. Each material we are going to create has a small reflective raytrace value together with a desired Fresnel setting. In addition, each material is utilizing the UV mapping mode for any used bump map.


The first material contains the main anisotropic specular reflection utilizing the new Tangent V function for specular highlights. This functions as the main base material. It also contains a low setting for raytraced reflections. It is very helpful to give your materials unique names to help you manage them.


(Image : Base Tangent)


In terms of texture you can either use an image map you create inside Photoshop (or other image editing software) utilizing motion-blurred noise, or you can use a procedural function. The benefit of a procedural texture is that it is resolution independent. I prefer to use voronoi. This texture can produce nice point patterns similar to noise. Using the the Int function you can decide if you want to use only dots or more a cell-like structure by playing with the Brightness and Contrast value. In addition, you could experiment with the Col1 option. With the internal texture scale value you can control the size of the points which will later be stretched.


(Image : Voronoi pattern)


You can now decide if you want to stretch the texture completely along one axis by turning off one axis inside the Map Input tap, or you can use the X-Z size values to scale the pattern down along one axis and stretch it along the other axis.


(Image : Texture Mapping)


This will produce the same visual result you would get with Photoshop anyway. The material is connected to one color input channel of a color mixer node which blends into the color channel of the output node. The next step is to create a second material that contains a diffused un-stretched specular reflection. This helps to build a multifaceted overall specular reflection which is typical for brushed metal surfaces.


This material we duplicate with each copy having a slightly different bump setting, then mix them together with color mixers. The end-result of this material network needs to be connected to the second color channel input to which the first material is connected. The amount of second materials will define the smoothness of the brushed metal look and also the smoothness of the anisotropical reflection.


(Image : Material Tree)


A schematic view would look like this:

Brushed metal shader tree: base shader with anisotropic specular second shader with sharp specular and amount of secondary shades with different bump settings


==Sealed surfaces: == Brushed metal surfaces sometimes have the problem of catching dirt because of the fine grooves. To prevent this you can seal the surface with a lacquer. This will result in a very strong and sharp specular highlight and a more soft looking anisotropic specular highlight. To get this result you need to lower the value of the anisotropic highlight and increase the value of only one regular specular highlight.



==How to unwrap: == Anisotropic highlights are often found on metal objects which represent geometrical primitives like a tube, a ball, a sheet or a box. Before we continue, I would like to present few important tips:


  • 1. Always try to unwrap the mesh from the side, or top view, but not from any perspective view to prevent any distortion of the UV texture you will apply. If your object or faces are not aligned to any axis, try to look perpendicular onto the faces you unwrap.
  • 2. To prevent distortions, always try to scale faces inside the UV editor to the same dimension they also have inside your 3d model. This is very important to keep in mind when you follow the next steps.
  • 3. You should hide the UV seam by either putting additional geometry over it or by rotating it away from the camera.
  • 4. Use seams to control where the mesh unfolds to have better control about where you will see the highlight break.
  • 5. Rotating a mesh in the UV editor will control orientation of specular reflections. Think about UV in only one direction. 'UV' could be upwards/downwards, and a 90 degree rotated version, lets say 'VU', could go left and right.
  • 6. To create smooth and even-flowing anisotropic highlights on curved objects, you will need to have a very smooth surface using either smoothed subdivisions or the subsurface modifier. Otherwise you will sometimes see sharp corners in the highlight.


? Plane: Unwrap > Project from view: This is the easiest object to unwrap. Just make sure you look perpendicular onto the plane.

? Cylinder: Unwrap > Cylinder from view: To texture a closed cylinder, I found it easier to create a tube and unwrap it first. After that step you should create a new loop cut very close to the edge of the end you want to close. Because you unwrapped the tube, the change in the mesh will already be updated in the UV unwrapper's mesh. Select the top loop of the tube and scale it down to close the tube by creating a cap. Do not merge the points. This way you can create a cylinder where the sides have a linear highlight pattern and the cap shows a circular high light pattern, similar to what we know from a CD.

? Box: Unwrap > Unwrap with seams marked before: A box is a pretty simple shape to unwrap. You only have four sides and two caps. However in contrast to a cylinder, the box can only provide you with linear highlight patterns. This also means that the cap will show a linear direction which flows from one neighbor face through the cap face to the other neighbor face. The other two faces will provide you with an anisotropic specular highlights which will not create a joint with the specular highlight of at least one cap face. If you take a small steel cube and try to brush each side with sand paper you will see that you can only connect 4 sides like a face loop. The other two faces will not be able to be integrated.

? Sphere: Unwrap > Sphere from view:═ A sphere is very easy to unwrap as well. Just go to the side view and unwrap it. You will notice that the poles show some darker artifacts. To fix that, remove the two top pole points to further open the sphere. Select a loop ring, extrude, and scale the selection down to close one pole. You should move the newly created loop ring to the same position of the vertices you deleted first to retain the sphere curvature at the poles. As with the cylinder, do not merge the vertices ring to close the sphere.

? Mixed shapes: Depending on your object you will have to utilize different unwrapping methods to get good results. In my test object I want to unwrap a cylindrical object which contains an extruded element.


Step 1: Building basic body:

Because you need to have a very smooth surface to receive smooth anisotropic highlights, I prefer to create cylindrical objects out of cubes utilizing the subsurface modifier to create the roundness. Starting with a box, I remove the pole caps and include two loop cuts. (Image 1)

I go into side-view and unwrap the box as a cylinder from view.


Next I re-size the faces in the UV editor so that they will be similar to the face size of the 3d mesh. (Image 2) We can now test out the first result. Turn on subsurf with a render value of 5, and create a material which has the Tangent V option, found inside the shaders panel, turned on. Set the objects' faces to smooth, and do a render preview. You will see a nice and smooth anisotropic highlight. (Image 3)


Maybe play a bit with the subsurf render value settings. Increasing and decreasing the value together with quick render previews will quickly show you how much the smoothness of the surface has an impact onto the smoothness of the flow of the highlight.


Step 2: Enhancing geometry and unwrapping:

Let's select one face and extrude it and review the result inside the UV editor. As you can see, the newly created faces do overlap and a quick preview rendering shows a bad result. (Image 4) We need to select the newly created faces in the face selection mode and unwrap them with "U > Unwrap". Going back into the UV editor we will see that the scale proportions are totally off and we need to manually correct that. (image 5)


Select all faces of your objects in the Face selection mode, go into the UV editor and scale down the newly added faces so that they will represent the actual dimensions of the 3D mesh. (Image 6) It is very important to keep the face orientations intact. Go into the face selection mode and select on face.


You will see two yellow, one green, and one red edge. Those red and green edges present the UV orientation. (Image 7) Select a face next to that face and you will see that sometimes the color change depends on the orientation. However, in case the lower edge of one face is red and the top edge of the face below is green in the Face selection mode - and in the UV editor it is the same, you will be fine, they overlap and share the same coordinates in 2D space. (Image 8)


In case in the UV editor the two edges do not overlap the faces will have different UV orientations and positioning and the highlight will now flow through both connected faces. (Image 9) I also rotated the face to show how that will affect the orientation of the highlight and any textures using the uv coordinates.


Apply a scaled down voronoi texture and stretch it along one axis while deselecting the axis inside Map Input which is perpendicular to your anisotropic specular highlight direction. Map the texture to the Normal channel, select the UV mapping mode, do a quick render preview and enjoy the nice effect. (Image 10) As you can see the highlight flows nicely over the geometry.


Step 3: Fixing texture flow:

However the procedural texture seems to have some bad seams. This is because we did not weld the newly added faces inside the UV editor to the faces of the cube. We have to do this now. Select the faces of the new extruded parts and move them into the hole of the unwrapped cube. Using snap to pixels will help with moving the faces. Stretch them so that they fill out that hole and then selectively weld the overlapping face points together. Do a test rendering and you will see that the procedural texture perfectly flows over the geometry.


(Image 11)


The drawback is that the last step distorts the proportional dimensions of the newly included faces inside the UV editor, thus distorting the texture a little bit. In other words, as you can see, the top sides of the extruded face shows stretched lines while the sides remaining have a finer grain.


Step 4: Finishing up:

Let us close the top cap. Similar to the cylinder unwrapping, just add an edge loop cut very close to the top edge of the cube. Select the top edge and scale it down until the edges hit each other. (Image 12) To make them perfectly touch each other use the CTRL key and release the mouse button when the scale value reaches 0 for x,y, and z. (Image 13) The last step is to include another edge loop cut close to the older top edge to create a nicely rounded edge for the pole cap. (Image 14)


(Finale Rendering: brushed metal)


Comments

This overview should show you how to approach the texturing and modeling as well. Try not to make your object too complex. Also, keep in mind that with a very good texture you might not need to show all geometrical designs. Drawing quad based wireframes of your objects before modeling them will help you to layout the design and might save you a lot of time at the end. Starting over from the beginning is always a hassle - especially when you realize that with a bit more planing you would have already been done.


Through the overlaying of the second materials we also receive some nicely glowing specular reflections specifically along edges as seen at the top edge of the cylinder.


Experiment with the approaches I showed you. For example, the UV editor is quite cool to play with in case you want to create some funny anisotropic highlight distortions. Let faces overlap or rotate other faces and then welding them rotated again into the main mesh. The results might not be very realistic or useful for representing a real object. However they might be very useful for something experimental or other applications in which you can see this working.


(Image 15)





2 Hammered metal shader:

Modeling of a bracelet:

To create a forged bracelet I taper the ends with a rolling press and planish them round. (Definition of planish: to smooth the surface irregularities in a sheet metal part with repeated hammer blows)═ This produces nicely tapered round cone shaped ends which can be textured. For that I use mainly a ball shaped hammer. Through texturing I convert the round cross section into the shape of an octagon.═


This shape has to be recreated through modeling. I start at the center of the bracelet and create an octagon. By extruding and evenly scaling down each new extrusion I can quickly build the main part of the bracelet. (Image 16) Turning on subsurf, setting all faces to smooth, and creasing the edges along the body will produce a nice and round body while the edges are sharp. I prefer to have a flat planished end which I roll into a loop. Because those ends are planished, there is hardly any texture left.


To model this I need to transform the octagon shape into a rectangular shape and move the center points to the sides in order to model the sharper edges. In the following steps I just gently scale down the thickness of the model and build a loop. (Image 17)


Because of the pressure applied during bending, the edges of the metal itself will roll up a little bit. In this case it might make more sense to leave the center points where they are and scaling down all those center points which define the loop. (Image 18)


We can use the edge crease option to selectively sharpen the edges of the bracelets. The edges along the loop have a high value to produce sharp edges, while the edges closer to the center of the bracelet have a lower value to produce a nice transition between the loop edges and the base edges. (Image 19)


Creating the shader:

Before we get deeper into designing the shader I would like to present some basic information which is important to know to gain full control over your shader creation.


Displacement > how to control the displacement :

Every displacement map should utilize a gray scale. Use the 'No RGB' option inside the 'Map To' panel to turn color bands into gray scale information. Black and white are the two different ends of any displacement movement. The value of the displacement will control the distance between these two ends. Depending on if you set the displacement direction (ie. working outside towards the inside of the geometry), white will either move polygons outside or inside. Black would have the opposite effect. Neutral gray will not move any geometry.


So it is advisable that you do not work with white to black transitions. Only use Black to neutral gray transitions inside the color band and selecting the No RGB option. This way you can easily control the displacement direction with the 'Disp' button inside the 'Map To' tap.


Stencil > how to control the blending of displacement maps :

To mix two different textures together you have to position a masking texture between them which has the 'No RGB' and 'Stencil' options inside the 'Map To' panel selected. The 'No RGB' will give you better control over the blending because the blending is based on gray values. The 'No RGB' option also enables you to use the color band function. White means it will be 100% transparent and black means it will be opaque. Gray values will represent the transitional values between white and black, in other words - between transparent and opaque.


As mentioned, we have a transition from a textured octagon shaped body into an untextured rectangular body.═ Creating a material like this would be easy. You would only need to apply a cell texture as a displacement map for the main body, a second texture map with a much lower displacement value, and a blending texture to blend those two displacement textures together where the model changes its cross section shape.


To my knowledge it is not yet possible to mix different channels of materials together utilizing the displacement information. Currently only the color output is supported. Fixing this limitation will allow the creation of a layered shader with different displacement settings utilizing the node system.


A schematic view would look like this:

Hammered metal shader tree: mixing

  • channel one : 1. displacement texture (strong value voronoi)
  • channel two : stencil texture (hand-painted uv map)
  • channel three : 2. displacement texture (soft value voronoi)


This means that we will have to create a handmade displacement map which provides strong and soft displacement values where we need them. This is not very difficult and can produce very convincing results. With hand painted maps you also have more control over the end result. However they are also more time consuming to create.


Unwrapping and exporting the UV Face Layout:

All we have to do is to unwrap our bracelet and correct the face layout inside the UV editor. Start the UV Face layout script and save it by hitting F1.


(Image 20)


You can model one-half of the bracelet, and after texturing stitch a duplicate to the other end. The UV coordinates will be transferred to the duplication.


Preparing the texture baking:

To bake a displacement texture we need to apply a texture to the Color channel inside the 'Map To' tap. As we did earlier, I recommend the voronoi texture. Inside the Map Input tap I increase the scale for x,y, and z to create small enough faces. Because I unwrapped the bracelet first the procedural texture will nicely flow along the cylindrical body.


Switch to the UV editor and start the Texture Baker script. The bigger the file size, the sharper the end-result will be. Because we work with pixels and not a procedural map, you should make sure that your displacement map will supply you with enough pixel information to prevent a blocky look.


Composing the Displacement Map in Photoshop:

Load both images, the baked texture and the UV face layout file into Photoshop and compose them together in one file. Apply a layer mask to the baked texture image layer. Create an opaque to 80% transparent gradient, and fade the top part of the baked texture away starting at where the UV face layout map shows you where the loops of the bracelet start soon. Hide all other layers and export this image as a high res jpg file.


Creating a dirt map:

Hammered silver surfaces tend to get dirty in deeper grooves because of tarnishing. The higher hills are often just polished through wearing the bracelet. Those dirty areas also have a lower reflection value than the high and polished areas. Save the newly created composition as a new photoshop file and call it something like reflection_dirt_map. Apply a level layer effect and increase the contrast between white and black. You can also lower the value output by moving the slide at the black side a bit away towards more a dark gray. This will keep strong white edges while brightening up the darker areas. Dirt is never uniform so apply a monochromatic noise filter to the baked texture layer. Hide all other layers and export this image as a high res jpg file.


(Image 21)


Creating the hammered silver material in Blender:

Switch to the Material window (F5) and create a material and turn Ray Mirror on. However leave the Ray Mir value untouched. Select Blinn for the specular highlights and create a sharp reflection. First we will create a channel for the displacement map. Go to the Texture tap and create a one channel. Inside the Map Input tap select UV


Go to the 'Map To' tap and deselect Col and select Disp. Set the Nor value to 0 and set the Disp value to something like 0.045. Depending on the gray scale of your displacement map you might need to increase or decrease the Disp value to achieve realistic values.


Secondly we will create a channel for the reflection and dirt map. Add a second channel and also set the mapping mode to UV. In addition to the Col option, select the RayMir option. Selecting the last one will make use of the values of the reflection map to define which area of the bracelet will be reflective and which will not. Gray values will be the transition between reflective and not reflective. Leaving the Col option selected will show the dirt values where the surface has no reflection value. Nice how both work together though one image map.


(Image 22)


Switch to the Texture window (F6) and create an Image texture.═ Load the baked displacement map jpg file. Deselect Interpolation and set the Filter value to 0.1 to prevent additional smoothing of your map. Create an additional Image texture and load the reflection dirt map jpg file.═ While you're at it, deselect interpolation and set the Filter value to 0.1 To make working with textures easier you should select the auto naming function, or give each texture a unique name.


(Image 23)


And we are done. You can hit render to preview you results. Check out the shadows. They show the displaced surface of the bracelet.


(Finale Rendering: Hammered Bracelet)


Comment

Hand created objects often show a level of imperfection or irregularity in surface and shape. As you can see the final model of the bracelet shows some of those deformations. For example, each loop is different. I moved and removed some geometry. I did these steps after I merged both half shapes of the bracelet together. This way, I saved the time to create two custom sides first which also would have required me to create custom made image maps as well.


You should only do this after your are basically done with your model and texturing it. Furthermore, I did paint a bit into the displacement map to flatten out normally displaced areas. Through the process of bending the bracelet, I also planished out some areas of the textured surface. Using a hand painted displacement map gives you the ability to quickly show those irregularities. With a pure procedural map, you would not be able to do that so easily.


==Displacement Modifier: == The next version of Blender will have an interactive displacement preview. This displacement modifier will enable you to see the displaced geometry in realtime. The subdivision modifier level will affect the precision of the preview. The higher the level, the finer the detail, but it will be slower. This is great for smaller objects but not very fast to preview many at the same time. However, you tend to only work on one object at a time anyway.


Procedural textures or image maps are supported. Because Blender also comes with a built in paint module you can create your displacement image map in Photoshop, apply it in Blender to the displacement Modifier and preview the result. In case you need a little modification you can load the image in the UV/Image editor and paint changes.


Switching between Object and Edit mode will force Blender to recalculate the displaced geometry and to show the changes to the image through the 3D mesh. With the possibly very high amount of polygons, it makes sense that Blender does not refresh any change automatically.═ Fortunately, his modifier comes with a very handy feature - It can bake the displaced geometry. This means that you can turn your preview into a solid new mesh and continue modeling with it. This enables the artist to use the displacement function, not only as a render time effect, but also as a solid modeling tool. With this tool, matching other objects to displaced geometries is finally not a nightmare!


Warning:

There is one down-side. Your scene file can quickly explode in file size. While my low polygon bracelet scene is around 1 MB a backed displacement geometry will add an additional 242 MB! This means that this function is great when you apply it to a small selection of objects without the highest subdivision level value.




3 structured and darkened silver surfaces found with casted rings:

Very common for casted silver jewelry which show a high level of details is that it is difficult to keep them clean.═ This causes a darkening of these areas which are hard to reach with a sulfur based chemical. Through wearing the ring all high points of the ring surface are going to be polished.


So what we would need is a material which provides a smooth polished and reflective surface for the main body and a material for the decorated area which shows a displaced surface, having a reflection value for the high points and a colored and non-reflective value to the low points of the displacement map. In reality those two different materials do not blend into each other. This means that we do not need to create any blending between them in Blender. To apply those two different materials to the ring we can simply create two different material indexes and apply them inside the Edit mode to different face selections of the ring geometry.


Select all of the faces which represent the main body of the ring and hit 'New' and then 'Assign' inside the Link And Material tap. Inside the modeling window press W and click Select Swap to select the other faces which will be displaced. Hit New and Assign as well.


(Image 24)


You now create the two new materials, then assign those materials to two specific areas of the ring. Most ring designs can be modeled as a low polygon cage with quad faces that we will be smooth utilizing the subsurf modifier. Through adding loop cuts we can pick out layout areas which will receive different textures. With some push and pulling you can quickly create some nice looking and comfortable to wear ring designs.


(Image 25)


==Time to create the materials.== A schematic view would look like this:


Structured metal shader tree:

  • Main mesh faces: base material with silver settings
  • Detail mesh faces: structured material with additional silver settings
  • channel one : displacement texture
  • channel two : inverted displacement texture
  • channel three : color texture for darkened silver



We already created the material index for the ring. Switch to the Material window (F5) select the first material which represents the majority of the unstructured ring inside the Links and Pipeline tap. Rename that material to something meaningful, like "Main body". Set the Object color to black. To rebuild a perfectly polished silver surface, turn on Ray Mirror, set the RayMir value to 1.00 and create a sharp specular highlight with the Blinn shader.


Even perfectly polished surfaces often still have some fine grooves and scratches. Through buffing you smooth out the sharp edges of those scratches and those produce a more even reflection which gives you the impression of a scratch free surface. An easy step to create that effect is to quickly unwrap the faces of the main body. Apply two loop edge seams along which Blender will cut the ring apart.


(Image 26)


Switch to the Texture window (F6) and create voronoi texture. You can scale it down a little bit and activate the Colorband option under the Colors tap. What we want is a bump map which only has few scratches here and there. For that set the black color Alpha value to 1.00 and turn cyan into pure white. We still have that cell structure grain typical for voronoi. Move the black color two thirds to the right side and the white color to the full left side. Know we have a nice black surface with some dots only. It might make sense to rename that texture something like "Voronoi Scratch".


(Image 27)


Switch back to the Material Window (F5) and apply the newly create texture inside the 'Map To' tap only to the Nor channel and give it a very low Nor value. Inside the 'Map Input' tap, set the working axis for your model to a high value. This will squeeze the bump map to produce a brushed look. In my case I selected the Y axis and used a size Y value of 40.


(Image 28)


Now it is time to create the displacement material. Inside the Links and Pipelines tap, select the second material. Rename it to something like "displaced". Turn on Ray Mirror inside the Mirror Transparency tap but leave the RayMir value at 0. We will create a texture which will define the reflection values. You have to decide which procedural texture plug in you want to use for the displacement. In my case I selected a Musgrave. Play with the NoiseSize value inside the Musgrave tap to create the desired pattern size. Switch to the Colors tap and turn on Colorband. We only want the displacement go into one direction.


It should either rise away from the ring surface or it should sink into it. For that we need to set the colorband to a gradation between black or white to neutral gray. You can move the black slider away from one side closer to the gray point to define how soft the transition between untouched and displaced geometry will be.


(Image 29)


After you made your decision it is time to create a blending mask. Select click into an empty channel inside the Texture tap and select the same Musgrave texture from the Add New menu. Click the 2 next to the small car icon to turn that instance of the texture into a single user. Go into the Colorband and move the black and medium gray slider a bit to the left. Add another color position and set that one to white and move this one a tiny bit away from the right side. You just created a mask which has slightly smaller holes than the displacement map through which the next texture will be visible through.


(Image 30)


The last texture will be a dirt map. Select what ever procedural and image texture you want to use. I used a strongly scaled down voronoi texture and set the colors inside the colorband to black and dark gray to produce a very fine and hardly noticeable grain look.


(Image 31)


Go back to the Material window (F5) I stress again to make use of naming each texture to make managing your channels much easier. Select the first channel with the displacement map. I set the Disp option to move faces away from the ring inside the Map To tap. Select the 'No RGB' button, set the Nor value to 0.00, and select a very light value for the Disp. I use 0.02 for example.


(Image 32)


Select the second channel with the masking map. Deselect Col inside the 'Map To' tap and click 'Stencil' and 'No RGB'. Turning both on will make white transparent and will also enable the colorband.


(Image 33)


Select the third channel with the dirt map. Double click RayMir. This will set the RayMir function to work on that part of the texture we did cut away through the masking map inside the second channel. This way the third channel will show the dirt map where we masking map did not key out and as well show the reflection. Furthermore does the texture we created also provide us with all needed RayMir value.


(Image 34)


Having all those channels set up check out the Preview tap. Looks great doesn't it?


(Image 35)


Inside the Editing (F9) window select the Subsurf option and give the render option a value of around 4 to 6. The higher the more precise your displacement will be during render time.. (Finale Rendering: Structured Ring)


Comment

When you work with perfect reflective surfaces it might make sense to give the different materials different base colors. This way you can see where you applied which material to which faces inside the 3D windows. I find that very convenient to work with. The higher the subsurf value, the more precise the realtime preview.


When you work with reflections you always need to take the environment you put the ring into also into consideration. Your raytraced reflections have to reflect something. Quite often, raytraced objects do not work out for beginners because they only created the shader for the object, but did not continue to think about what those reflections will show. Putting the ring into the right setting will often drastically improve the quality of those reflections.


Soft irregularities inside reflections created through a second very blurred bump map will often increase the realism of reflections. There are hardly any perfectly flat surfaces in reality. Raytracing tends to produce those perfect visuals. As an artist you have the task to bring nature's irregularities back. Those fine details are often the key to producing realistic results.




Compositor based depth of field rendering:

Small object studio photography makes high use of the depth of field effect to diffuse distracting background elements and to put focus on the main object. We can reproduce this effect with the compositor. There are two ways you could do it.═ The old way uses the well known Z-depth blur trick. In Blender you would use a pixel based matrix created through the z-depth information to blur the render output. The problem you would encounter is that pixels of the edges of the object in focus will be mixed together with the neighbor pixels, which belong to the background.


A real DoF effect would not use a Z-depth based image, but would render pixels depending on the distance to the camera in relation to the lens settings. The final bracelet rendering shows that problem. The top edges of the metal surface are blurred as well. However a way to prevent that is to divide the objects onto different layers and blur only the layer with the background objects. With using an Alpha Over node inside the compositor you can than mix the blurred background together with the object in focus.


(Image DoF)


You just have to be very careful with not blurring also parts of the background on which the camera focus sits on. Otherwise you might see a blurred surrounding while the focus object is sharp. This would look physically wrong. In most cases you will only see a small amount of the foreground with object studio photography. This means that you can also ignore blurring the foreground.


The "Finale_Unwrapping" blend file contains all the required setups. Keep in mind that when you spread objects along render layers, you also have to make sure that all your lights also are active in those layers at the same time. Inside the Object window (F7) can select the different layers inside the Draw tap.


==For more information about how to setup the render layers go to:== http://www.blender.org/cms/Render_pipeline.747.0.html═ Look also into the other two jewelry blend files and you will find similar blur problems.


Z-Depth sample based blurring:

Recent changes in Blender brought to us by Alfredo de Greef brought us the new Defocus node for the compositor. From working with it, I got the impression that it seems to be a cross-over of the traditional Z-depth based blurring.═ It is not purely pixel matrix based, but rather uses samples like with a true DoF effect. The Z-buffer information seems to work as a helper in aiding Defocus to know where to sample. This will result in a sample mask which will only blur areas out of focus without bleeding into sharp edges of objects in focus. This is a enormous advantage over the old fake DoF trick because there are not artifacts and thus also no cleanup afterwards.


You can either use a traditional fStop like approach for blurring or you could use a Z-depth based image. If you go with the Z-depth image you can either use the Z information Blender provides you, or even supply the Defocus node with any other information of your choice.


One great advantage over the old Z-depth blur trick is that it's reasonably fast. Because it is a post production effect, you can use the preview function to quickly get a rough idea of the final effect. Depending on the amount of samples, the preview will be smoother or more grainy. For a final shot you only need to deselect preview and the compositor delivers the final result shortly after that.


(Image Defocus Preview)


Utilizing the Map Value node together with a Color Ramp node you can customize the z-depth image to make it fit your needs. The Map Value node sets the focal point while the Color Ramp node will adjust the size of the depth of field. And of course the nice Viewer node gives us a direct feedback on how the actually z-depth map looks like. And with the Zscale value you have control about the strength of bluring.


(Image Defocus_custom_z-Depth)


The fStop option is similar to what everybody knows from real cameras. A value of 128 will set everything sharp while 64 will double the amount of blur according to Alfredo. This is for controlling bluring. Depending on your scene you might have to go down to values like and fStop of 4 to see the blur effect. To control the focal point the camera has a new option which is called DoFDist . You need to turn on show Limits for the camera to see the focal point. It is presented to the user as a yellow cross. Increasing the DoFDist will move the cross away from the camera.


(Image Defocus_fStop1 and Defocus_fStop2)


This is a very comfortable and precise way on how to control the focal point and also knowing where it really is in contrast to the old fake trick. But sometimes, depending on how you set up your scene and from where you point your camera, not everything seems to be in focus. The Defocus node comes with two tools which can be used to clean up artifacts but. Those are the Maxblur and BThreshold. However those tools you can also use to make the focus wide/longer while remaining the amount of blur as well.


Take a look at the Car_Interior.blend file. There you will see that the right part of the gear stick is out of focus.


(car_Interior_defocus_artifact_1)


Increasing the BThreshold will move the edges of the focal point more apart.


(car_Interior_defocus_artifact_2)


But as you can see there is also a blur artifact on the panel. The out of focus area starts too fast and there is no transition between in focus and out of focus. You can fix this with using the Maxblur option. This will smooth out the edge.


(car_Interior_defocus_fixed)


As you can see the complete gear stick is in focus and the foreground and background are nicely blurred. Because Defocus is a post production effect you can also just adjust the camera DoFDist value after rendering, and the compositor can re-calculate the DoF effect again without re-rendering the complete scene. For more information look here: http://blender.org/cms/Composite__Defocus.836.0.html




Car interior study:

(Image Car Interior)


This image shows the types of geometries you might come in contact with. Cylinders, panels, and other basic shapes. Lucky us, those elements are easy to unwrap. Take a look at the scene files and how the individual objects are unwrapped to get an idea about how you should plan ahead you models for texturing. It can be a very big pain when you realize how difficult you made the object to unwrap.


The key to metal surfaces are smooth and flowing highlights and thus do you need continuous surfaces as well. Try not to make objects out of one mesh. It is helpful to study the construction and assembly of products before you try to model them. You will find out that many elements are made out of shells. Two shells can produce on container.


The gear stick panel is made out of one shell. I would rather try to model all elements separate. This way the UV-unwrapping and texturing will be much easier and more successful. Be aware of the relation between texture and object size. As you can see, the texture looks much more rough on the panel than the gear stick. Explore the scenes and you will see how simple the actual approaches are.


Looking at the gear stick in the UV-editor you can see how where I decided to apply the seam along which Blender cut the mesh apart. It is behind the stick and thus cannot be seen in the rendering. I used the unwrap function. Looking at the panel shows you how the downwards extrusion to make place for the gear stick to slide in is integrated. In this case no complex work was needed. The panel was unwrapped using the unwrap option. Looking at the air vents shows you that not everything needs to be perfectly unwrapped since you will not zoom in far enough to see the imperfection.


They were unwrapped with the unwrap function using a seam. The Car Interior 2 blend file includes the same scene just with modified shaders to show how sealed surfaces could be rendered. This is a quick setup explaining a possible approach. Take a look at how fine the brushed look could be and how it works together with the richness of the wood. The combination of different specular highlights adds additional readability for the viewer to understand the geometry and also the material properties.


(Image Car Interior 2)

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