gonzo wrote:
> Vincent LE CHEVALIER <lec### [at] ctiecpfr> wrote in message
> news:4058196c$1@news.povray.org...
> 
>>Hello !
>>
>>I've been trying to render the same landscape in POV-Ray and Terragen,
>>and I found myself stuck in the texturing. I wonder, in fact, if there
>>is a way to do the same texturing in POV and Terragen.
> 
> 
> Been trying to do the same thing... Terragen textures really add a lot...
> 
Yes, and POV could add a lot to a Terragen texture. For example, a shiny 
finish, and several different shapes for bumps. That's what gave me the 
idea first.
> 
>>As far as I understand, Terragen's textures are organized in several
>>layers, each with a specific color and amount of bumps. So far, layered
>>textures would do the trick. The point is that in Terragen, you can
>>control the visibility of a layer based on the slope of the underlying
>>layers. For example, you can have a rock layer, very bumpy, and a snow
>>layer over it, only in the less slopy areas, with its own bumps.
>>
>>I tried to achieve such effect with a slope pattern in a layered
>>texture, but in this case the slope used is just that of the
>>height_field, not including the normal perturbation.
> 
> 
> I'm pretty sure Terragen uses the height_field slope to determine it's
> layering also.

Sure. But it seems that Terragen uses somehow the slopes simulated by 
the normal perturbation as well. You can see that when you modify in 
Terragen the amount of bumps in a parent layer.

> But I think Terragen interpolates its maps differently than
> POV does.

I really don't know. But whithout bumps, Terragen terrains do look like 
smooth height_fields in POV. Nevertheless, I tried to render the exact 
same terrain without textures, atmosphere or ambient light, and I 
noticed indeed a slight difference. The terrain does look smoother in 
Terragen.

> 
> 
>>I can obtain something similar using slope-patterned pigments and only
>>one normal statement, but then I lose the control over the bumps of each
>>layer.
>>
>>Has anyone got an idea about how to solve this problem ?
> 
> 
> Still playing around with it, but I've had better results with texture maps
> using a mix of slope & gradient than with layered textures (I still haven't
> figured out how to get as much control over layers...), and I'm just
> starting to play around with normal maps.  Terragen's texture editor layers
> things by both slope & altitude, and I find the gradient pattern useful to
> reproduce the altitude.
> 

I believe you can take the altitude dependency into account when using 
the slope pattern. The optionnal altitude keyword allows to add the 
effect of a gradient into this pattern.

Thanks for your answer. I will keep trying...

-- 
Vincent

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