Archives for April, 2008
Tutorial: Creating Photo-Realistic Renders with HDR using 3ds max & Mental Ray
Wednesday, April 23rd, 2008
The technique I use to create photo real product image renders is called Image Based Lighting (IBL). There are no lights in the scene, all of the illumination is provided through the HDR texture map. The images above are some recent 3d models I have rendered using Image Based Lighting with an HDR map I created. I have this HDR image probe available for a free download as you go through the tutorial.
First thing you want to do is start with a fresh scene and merge in the object that you want to render. I’m going to use a wall sconce that I modeled recently. If you don’t have any 3d models off hand, just create a few spheres or a teapot and apply a shiny or glossy shader to them. Try to keep a realistic scale to them, for instance, give them a 3-6″ diameter. This goes for any model that you merge in -make sure it has a realistic scale. If you don’t already, everything you model should be to scale. It helps textures, lighting, and cameras play nice together -not to mention adding realism.
HDR with 3ds max & Photoshop: The basics
Saturday, April 19th, 2008
Over the last few weeks, I’ve been learning more, and applying more HDR techniques in my work. I’d like to post some tutorials on how to work HDR techniques into 3D renders, but first I want to go over some basics before we jump into the step by steps. Also, keep in mind; HDR can get pretty deep as a topic. There are lots of ways to take advantage of HDR imagery, but I can only share what I’ve learned and how I take advantage of it. If I’m missing anything about the theory or process, please let me know!
Now, without getting too technical, here is how Wikipedia sums it up,
…High dynamic range imaging (HDRI) is a set of techniques that allows a greater dynamic range of exposures (the range of values between light and dark areas) than normal digital imaging techniques. The intention of HDRI is to accurately represent the wide range of intensity levels found in real scenes ranging from direct sunlight to shadows.
Using HDR images in your 3d work can help your renders look extremely realistic, however, outputting your renders in an HDR format also allow for greater post-production flexibility. The part about, “..allows a greater [...] range of values between light and dark area[s]” is the key here. An HDR image holds information underneath the bright white areas in an image -this here is why I see so much value in using HDR imagery in my work. Take this image for example: 
See the white areas in this image? Since this is an HDR image, there is image data underneath (or inside) that can reveal more of the environment that was caught in the reflection. An image with a standard dynamic range, your basic .jpg for instance, would only be able to turn those white areas grey, revealing no new information.
Turning down the exposure in a capable image program can reveal what’s hiding underneath the white in a true 32-bit HDR image.
This is what happens when you try the same thing using a typical image with a standard dynamic range. No new information is revealed in the white, it just turns grey.
Next is the tutorial where I’ll get into how to create and output HDR images with 3ds max, as well as some HDR post-production techniques in Photoshop. Until I get to that, here are some good links to learn more about HDR:
- HDRI on Wikipedia
- Paul Debevec’s Site - This is the authority right here. Check out his bio.
- Earthbound Light - Great write up on shooting images in HDR and file format details.
Here’s a full res of the above image. This is an old character I created while at the Art Institute of Dallas. It’s called a Triavera.
hdr_global-illumination-and-reflection-copy.jpg
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