Strange Render Artifacts

[chrisS@422]

Hi guys,
I'm getting very strange artifacts in my renders, when I'm close in with the camera (roughly 2-4 meters across frame) there is some sort of sampling issue? It occurs after the final prepass. Im using PF's all the way pretty much apart from my DEM. Ive tested each node and rebuilt the scene from scratch, yet it still keeps appearing, It seems to be distance from camera based.

See bottom of frame...
Test_38.jpg is displacement and shaders, about a meter or 2 from the ground
Test_39.jpg the same
Test_41.jpg is base colours and DEM only,
test_41a.jpg base colours only, no displacement or shaders

Any Ideas?

Thanks
Chris

[fleetwood]

This may be similar to the grid artifacts at small scale I encountered in a render where the camera is at very close range - only spans a meter or two.

Matt's explanation of that :
"I think it's being caused by "noise variation" in the Power Fractal combined with very small scales (around 1mm). With Kadri's file I was able to make it happen with just the Power Fractal, without Fractal Warp Shader and without Compute Terrain. But I couldn't reproduce it when I set noise variation to 0.

Unfortunately I think you're just reaching the limits on how far you can zoom into a Power Fractal. I don't know if this is something that can be fixed. But I guess that with smaller numbers for "lead-in scale" you might be able to zoom in closer.

Matt"





It is discussed here --->   http://www.planetside.co.uk/forums/index.php/topic,18196.0.html

[chrisS@422]

Ah,
I was wondering if it was something along the 'too close' lines, very useful reply thank you fleetwood!

Chris