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tomek_zielinski

Making textures from photos

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I've got a question - how are you doing this? I have a buch of photos each one with different lighting. First I need to make the lighting uniform. Then I need to make them a bit 'unreal' (like in all games - colors like Hawaian see etc). Is there a path to follow, some filters or it should be made by hand?

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I saw an article somewhere about using a high-pass filter (basically, an inverted low-pass, IIRC) to remove broad lighting variations, but I can't remember where I read it and I don't know if your image editor of choice implements a high-pass filter. Barring that, you can attempt to even out those lighting artifacts by hand by using the Clone / Rubber Stamp tool to copy portions from other areas of the texture. Ideally, though, you should try to take photos with the lighting as even as possible.

For coloration, you can create a new layer on top of the original image, then experiment with the different layer 'modes' and fill colors. For instance, a layer filled with a dark green set to Overlay can 'greenify' a shot of grass that looks faded. Other modes that can be useful include multiply and soft-light. To get variation, instead of using a solid-filled overlay layer, try a greyscale noisemap instead. The noisemap can be blurred and blended for interesting variation.

One trick I like to do in the Gimp:

Start with the ground texture. Create a new layer, and use the Filters->Render->Clouds->Solid Noise filter to fill it with a random cloud map. Create another new layer and fill it with a solid color. Set this third layer to multiply and merge it into the second layer. Then, set this second layer to Overlay, and merge it down onto the original. Plasma Clouds can be fun, too.

The trick is just to play with whatever filters and effects your package offers.

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Thanx for detailed answer! Thank god it's not black magic:)

With that lighting I meant not lighting differences within single photo, but across several photos(for example one taken in the mornig and one in the evening). How to filter several photos and make them looking like shot in similar lighting conditions?

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im not familiar with GIMP, I use PS7 for any texture work and at that rarely us photos for textures instead choosing to paint my own, but if its simple procedural textures your looking to setup then this website has some good tuts on photo manipulation which will help (all PS tuts): http://www.3drender.com/index.html

hope this helps.

Gordon

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Hi,

You should probably play with the HSB model (Hue-Saturation-Brightness) and/or Brightness/Contrast filters. I mean, that's how I would do it with Photoshop, I am not sure if you have similar controls in your editor. As a general guideline, search for filters that bear on brightness, even those in which you can design the curve by inputing control points. Those can fine tune your picture. As for "alien" colors, just play with the Hue part of the HSB control. It replaces ranges of colors with others, very smoothly.

Hope this helps.

Tudor

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Thanx once again!

And once again I've got question:): how to determine if image needs correction and how much? For example asphalt is much darker than marble with the same lighting, so how to find out if relation between their brightess is correct? Do I need to use histogram or some other tools. Or I need to learn to "feel" such things?

EDIT: I need this form my game. I would like to have all textures lit at the same level so that lighitng in game engine will produce real results.

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Hi again,

What are you exactly trying to do?
Is marble and asphalt from same picture or different?

If same picture, you're in need for a professional graphics artist since the picture would need to be processed by each containing item.

Numbers on brightness slider from HSB filter on Photoshop may give you an ideea (sample with sampler first), but I think you need to equalize by ear.. uf, eye. I am sure there must be mathematical equation that should help you do that with perfect accuracy, but I do not know what it could be. Perhaps you could get an average of brightness of several pictures and input it on a average equation (a+b/2). A good eye is all you need in most cases, anyway.

But then again, I am a programer, not a graphician, so I could be wrong.

Tudor

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Hi. We're now trying to do what you said. I thought that for example guys that were making Max Payne and had thousends of photos had to do this automaticaly. We haven;t got so many photos so it's not such a huge problem, but I asked in case auto-processing is somewhere out there

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