Well after some experiments with Brazil Advanced and HDRI, I thought I'd share the best way to go about making a render with it for those of you who want to try.
First thing you'll need to do is to update all your materials to Brazil Advanced, and change the Base Shader to Car Paint. You'll have to reload the textures to do this. Do them one a time, and once you've added your texture to the
color slot, drag it down to Candy, and Falloff as well. You may need to change the colour of the Candy and Color settings if your texture is white, as it seems that the colour affects the brightness, and in the case of the Candy colour, the Pink bleeds through the texture. I recommend a mid-grey, that should give you a good trade-off between brightness and contrast.
If you are using a model from my previous tutorial, and have a white box over the car, delete this, as it will just increase rendering time and will make the render look pants
For the reflections, change the Reflect colour to white, and change the IOR to 2. If you want to change how reflective it is, change the IOR number. If you're just experimenting with normal primitives (sphere's, torus knots etc) then here's what approximate IOR values are equivalent to:
IOR = 20: Chrome
IOR = 10-15: Brushed Metal (gold etc)
IOR = 5-10: Car paint (no textures)
IOR = 2-5: Car paint (textures)
IOR = >2: Glass / low reflectivity objects
For tires, keep the Base shader as Brazil Default. Then change the reflect colour to a very dull black (HS
V 35-45). Then go to Advanced Reflection Params and activate Glossiness, and tune it down to roughly 20. This will blur the reflection, and make it seem more tire-like, as it won't be reflecting specific details of the HDRI used in the reflection.
Once you've done this for all your textures, you can go about setting up you HDRI. To do this, pick an empty slot, and click "Get Material" (the blue sphere with an arrow pointing to it). Then select Bitmap, and your HDR image. Take careful note of what the white point value is, as you will need to put this into the RGB level slot in the Bitmap Output Params. For example, if it's 20, you scroll down to Output at the bottom of the screen, and type 20 into the RGB level box, this will make your HDR image the correct brightness / contrast for best results. Higher than the white point value will make your reflections very bright, and perhaps overwhelm the textures if it's too bright. If it's below the white point, it will reflect with very little "punctuation" to the reflection. Now open up the evironment menu (keep the material editor open) and drag your HDRI map into the map slot. In the Co-ordinates rollout, change the mapping type to "Environ" and then in the box, cylindrical, or spherical mapping. Different maps are made for different Environ maps, so experiment for best results.
Next, we need to set up Brazil for some better results. Recently, I've been playing around with getting better looking shadows. The best technique I've found so far, is to have a Brazil directional light, Shadows on, and then with the specular surface settings turned off, and the diffuse as close to 0 as possible. When shadows are turned off in the Skylight settings, this seems to give a better result with shadows.
Go to the Luma Server and uncheck the "Allow Default Lights" and "Enable Shadows" box. Then, where it says View Rate and Sec, change these to 25 and 20 respectively. Then go to the Image Filter Rollout and change it to Catmull-Rom, this is a sharper filter than the one that Brazil uses as default, and it produces (imo) the best results, having experimented with all of them.
Another thing to do (if you have a white scene) is to go to Render Pass Control, and turn it on. Then go to environment settings, and change it to White. This will mean that your HDRI map does not show up in wide-angle shots, or shots where it is likely the map will be shown. If you are doing a scene with asphalt or something else, then experiment in Photoshop / PSP / Gimp with the background to try and get the best results.
I'll upload pics and find some links to a few free HDRI images. You'll also need a little tool called HDR shop, which lets you edit HDRI images in an image editor, and means you can change the resolution of the maps in order to speed up the render, or to get better results with an ultra hi-res map.
Another technique with HDRI is HDR lighting. This involves putting the map you added to the environment slot into the Skylight as well. It is designed to simulate real world lighting, and depending on the map used, will change the colours in the render depending on what range of colours used in the map. For example, a bright, "hot" map (ie, a map which is predominantly red / orange / yellow etc "hot colours"
will give the render a hue to match. The opposite would happen if you had a map that was predominantly "cold" colours.
One thing to bear in mind when experimenting with HDRI lighting, is that it
will increase rendering times. In my case, it increase them pretty dramatically because I have a poor PC, but in any case, rendering times will increase. Another thing to bear in mind is that you'll have to tone down your skylight value, otherwise the render will be too bright and will look washed out. Experiment with values, it changes from map to map, and while a value of say, 0.5 will work for one, it might be too dark for another map
When I get home, I'll update with a few pics and links, for now though, enjoy HDRI
-EDIT- [
www.lightworks-user.com] Click on Image Files and download the panorama's imo, they work best with cylindrical mapping
And HDR Shop: [
gl.ict.usc.edu]
Edited 2 time(s). Last edit at 05/18/2006 11:46AM by zeppelin101.