Power Fractal - "An unknown error occurred in TrueRay"

[penboack]

I am experiencing a problem in Terragen V2.4 build 2.4.32.1 on OS X 10.7.4, where in the project I am working on if the Smallest Scale on a Power Fractal in my Shader network is below a certain size the Errors and Warnings menu pops up with the message:

"An Unknown error occurred in TrueRay"
"An unknown error occurred in trBucketRender::RenderMore() rasterised pass.

Any idea how to fix this?

[penboack]

I found a way to reproduce this:

Open Terragen 2, LMB Click the Terrain tab.
Delete the Heightfield shader 01.
LMB Click Add Terrain > Power Fractal.
LMB Click the Water tab and add a Lake.
LMB Click the Shaders tab and Add Layer > Surface Layer.
LMB Click Add Child Layer > Colour shader > Power fractal shader v3.
In the Power Fractal settings add zeros after the decimal point to the Smallest Scale.
When the Smallest Scale is changed from 0.01 to 0.001 the error message pops up and the 3D Viewport is no longer rendered.

Project file attached.
The scene will throw the error when opened.
Changing the Shader > Surface Layer shader > Power Fractal > Smallest scale from 0.001 to 0.01 will stop the error and the 3D Viewport will render.

Please could someone investigate.

[jaf]

When the Smallest Scale is changed from 0.01 to 0.001 the error message pops up and the 3D Viewport is no longer rendered.

Maybe I'm behind the times here, but I believe that's a common problem when you "pump" very small values through the algorithms.   I remember trying to track down the small number thresholds and found it varied depending on the other numbers (well that's confusing and won't help!)

I thought I could look at the xml code and figure out the rounding (is .0001 the same as .00011?)  This was a while back and I guess I just started staying away from numbers that small. 

[penboack]

It only happens if there is a lake in the scene.
I also tested in Terragen Free Edition V2.3, Build 2.3.21.1 with the same result.

[Zairyn Arsyn]

i think the same thing happens when i input a 0 (by accident) in any of the noise stretch input boxes

never seems to cause any serious problems.

[Oshyan]

A setting of 0.001 for smallest scale tends to cause issues. But consider whether you actually need millimeter-scale features. Everything is measured in meters, so 0.001 is 1 1000th of a meter, or a millimeter. It's very unlikely you actually need to use scales that small.

That being said of course TG should handle this situation more elegantly, perhaps imposing a lower limit on scales.

- Oshyan

[TerrMite]

Hi,

Late input but according to earlier posts the limit is 5mm = 0.005.