Photos To Textures - Part 1
Eliminating Lens Distortion

The Camera

Many texture maps are derived from real world textures. That means that a good texture starts with a good photo and good camera.

When I first started producing textures, for my own 3D work, I had an Olympus D360L digital camera. Although it's 1.3 Megapixels (1280x960 pixels), might be an adequate final resolution for most textures, it's generally best to be able to shoot at 1.5 to 2 times the resolution you'll need for the final product. This allows for some cropping and processing, while maintaining quality.

Olympus D360-L

Nikon Coolpix-995

Photo taken with D360L showing Lens distortion

Taken with Nikon at full wide angle showing similar distortion

Correctly taken raw image

Result- a crisp, detailed tile which adds realism to your scenes

The lens of the D360 is small, and is of fixed focal length. It's permanent setting is that of a slight wide-angle, and exhibited some lens distortion. Olympus provided a filter which actually corrected this distortion as a part of their Camedia software, however, the edges of the photo would show some signs of fuzziness, lowering the quality of the photo, and making it especially difficult to turn into a seamless tile.

Nowadays, I use a Nikon Coolpix 995. This camera is wonderful. It's resolution is 3.3 Megapixels (2048x1536), which gives plenty of lattitude if you need to crop the image, as you'll still end up with a high resolution final result. It's got a much larger and higher quality lens, which provides crystal clear shots from edge to edge.No lens is perfect, and that goes for the Coolpix 995's as well. This lens shows distortion at both ends of the zoom spectrum. At full wide angle setting, square objects bow outward, as in the photos below. At full zoom, there is a negative bowing, and the lines pull inward towards the center.

Neither of these zoom settings is adequate for creating a seamless tile. However, when the zoom is set exactly in the center of the range, this distortion disappears, and square objects once again appear square. When taking photos of objects that need to tile seamlessly (bricks, floor tiles, windows, doors, etc), it's critcal that the distortion is corrected in the camera by finding the correct zoom setting. Otherwise, it will be virtually impossible to create a clean, seamless tile.

If you've got lots of legacy raw images that you need to turn into textures, then it may be of use to pick up a 3rd party Photoshop plug-in that specializes in fixing lens defects. Andromeda's Lens Doctor does a decent job, and can be incorporated into a Photoshop action to help you automate the process.

I took this photo incorrectly on purpose to show you how even having an expensive camera won't help you if you don't do a little testing and calibration first. Although I can easily fix the color and perspective (I'll cover those topics in the next few lessons), fixing the lens distortion is much more difficult.

However, it's my philosophy that if you can re-take the shot, do it. It will be much easier to work into a useable texture if you are dealing with an image with no lens distortion to start with.

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• How to hand craft realistic bump maps
• Using alpha channels vs. transparency maps
• Creating Textures: Color Correction
• Creating Textures: Perspective Correction
• Making your textures seamless
• And many more...
  

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