Understanding 'diffuse color'..by definition?

[yesmine]

I'm still new to Terragen and realizing that my interpretation of the meanings of terms isn't always what it may be in the program. In this instance, my take on 'diffuse color' was that it would dull or muddy any colors in my object--make them more diffused. But I saw a post suggesting 'diffuse color' simply meant darkening or brightening the existing color? If that's the case, then is there more in being able to change the little color selector box to some other color? That sounds like changing hue or tint rather than simply diffusing (or maybe that does muddy or shade the original color too, i.e. diffusing it.)

The same kind of questions with 'translucency'. ? I'd expected 'translucency' would be simply a more-or-less option, so if I change the color selector, does that actually change the color of (e.g. a leaf) when sunlight appears behind it? As long as I understand what's happening, more control is better I suppose.
Thanks..

[j meyer]

In case you don't know there is a wiki with descriptions of the nodes and other
helpful stuff.
This is for the default shader:http://planetside.co.uk/wiki/index.php?title=Default_Shader

Edit: Sorry it should have been a working link,don't know why it doesn't work.
       You'll find the wiki under User-contributed Tutorials ->in the sticky thread.
       

[jo]

Hi,

Diffuse colour is essentially the basic underlying colour of the shader. So if you want green grass you use a green diffuse colour. Often there are a few settings available with diffuse colour settings, for example you can set the colour using the colour picker, an image map or another shader. All of those settings combine to set the basic colour of the shader. This is explained more in the Default shader docs j meyer linked to:

http://planetside.co.uk/wiki/index.php?title=Default_Shader

There are other aspects of some shaders which influence the final colour you see from the shader, specular and luminosity settings for example, but the diffuse colour is always the basic underlying colour.

Diffuse has a special meaning for materials or surfaces in rendering. You might be thinking of "diffuse" in the terms of diffusing light like using a frosted shade to soften and spread light. However diffuse means something else for surfaces. I guess the best way to say it might be that it's the matte non-glossy colour of an object under a pure white light. You might like to do a web search for "diffuse rendering" or "diffuse colour" to get a better understanding. Note that you particularly want to pay attention to things talking about diffuse colour with regard to materials, surface colour and reflection.

Translucency is explained here:

http://planetside.co.uk/wiki/index.php?title=Translucency

Regards,

Jo

[yesmine]

Thank you Jo and J Meyer, this has been extremely helpful (and I apologize for not having found the Wiki entry first). I'm having more success now, and it definitely pays to experiment and see exactly what the settings do.

For what it's worth, I wonder about the information in the Wiki stating that setting the 'Diffuse Colour' to white (1) is what will give the pure colors of the 'Colour Image'. I think I saw in another post or Wiki entry that setting it to .5 is what makes the Diffuse Colour setting have no effect (leaving the original colors of the image). At the moment I think the .5 info may be correct. I did some testing by creating two solid white samples for my 'Colour images', one tipped in red and one in blue, to apply to a grass .tgc I found. It seemed to me that .5 did give the purest colors matching the 'Colour image' white/red/blues.
Thanks..

[jo]

Hi,

The information in the Wiki is correct. The colours from the different sources get multiplied together so using a 0.5 grey diffuse colour will knock back the shades of the colour image by half. What is important to understand is that because of the lighting in TG colours from images are not necessarily exactly what you are going to see looking at the image in an image viewer. Images often appear to be brighter. You may need to adjust colours somewhat to get a result that pleases you. This might be what is happening when you use a 0.5 grey diffuse colour along with the image.

Regards,

Jo