• TechNotes
• Creating Textures from Simple Photographs

Techtip of April, 2008: Creating Seamless Textures from Simple Photographs

• - by Ralph Wessel, UK

(Editor's note: This techtip requires non-GS software, however, I considered it really useful - and Ralph's description is really explanative.)

I'm wondering how to create a brick pattern in English Bond (this is alternate courses of stretcher bricks and headers) in a multi-yellow colour. I believe you can photograph examples and map ??

Ralph's answer:

In addition to Karl's suggestions, you can make a seamless texture from a simple photo. You will need software for editing images, ideally something like Photoshop but there are cheaper alternatives.

To create a simple texture, like the one shown at the end of this article, follow Ralph's advice as set out below:

1) Take a photo of the target material with the lighting as even as possible.

The ideal is a slightly overcast day in an unshaded area, because you get a very diffuse, even light with good colour. It can help if the surface of the material casts some shadow, because it provides a measure of relief, but too much will ruin the effect.

Also, try to position your view to minimise the distortion from your perspective, because the end result has to appear to be a perfect elevation. (Decent software should provide tools to skew or deform the image to eliminate this distortion.)

When you crop the material sample from your photo, think carefully about the borders. It helps if they somehow align to joints or other repetitive elements in the material to minimise the cleanup afterward (and to ensure the sample repeats in even units). Also, avoid samples with one segment that is significantly different from the rest - when the texture is tiled, your eye will be drawn to the contrasting part and notice the repetition (almost like a dashed grid).

2) Software like Photoshop should provide a tool to offset the image, but every developer likes to use a different name for the tool. (The function of the tool is to offset or shift the whole image by a specified number of pixels, and the parts which flow off the edge are wrapped around to the opposite side.)

If you offset the image by approximately half its size, you will clearly see the tile junction running through the centre of the image. This makes it relatively easy to clean up.

3) Again, software like Photoshop will have something like a 'stamp' or 'clone' tool, which enables you to airbrush one part of the image over another. You can use this to great effect to clean up the tile junction by cloning similar (whole) parts of the image over the broken or ragged tile edges.

I've made many textures from site photos this way - invaluable for restoration projects or extensions.

You can see Ralph's texture creation process if you click on the below link (thanks Ralph for the splendid example!):

The original thread can be found at: http://archicad-talk.graphisoft.com/viewtopic.php?t=22483&highlight=tip