Spot light with image as a pattern

[DorPrz]

BTW after disabling the world light the "bad renders" went completely black.

[B.Y.O.B.]

I rendered 100 images with Path OpenCL and each one was correct.
However I rendered with OpenCL on CPU device because my notebook does not have a GPU.
The fact that it fails on your GPU could mean that your GPU driver has a bug in its OpenCL compiler.

I made some changes as I mentioned, if you want you can test it with the modified file if it also fails on your GPU:

[DorPrz]

I had 1 bad render on a CPU, Can you test a little more? maybe 1000 renders?

[kintuX]

Specifically testing Spot Light with image pattern (.bmp) on 100 frames.

It is rendering fine using OCL Path on GTX 1060 6GB.
Sys. specs: driver version 391.74, Windows 7SP1 x64, Blender 2.79b

Just not after first set of changes (applying realistic values).

1. World
=> None

2. Spot Light
Gain = 1
Power (W) = 1500, Efficacy (lm/W) = 17

3. Camera
=> LuxCore Imagepipeline / Tonemapper / Use OpenCL (on)
=> Camera Setings
F-stop: 4, Shutter (s): 1/20, ISO: 400

Results vary in lighting & 3 black frames.

Have observed similar behavior before, issues when Camera or lights are positioned on XYZ (0,0,0), so i checked coordinates.
Then, after another change: Spot Light moved on X to 0.01, all went smooth. Right.

Am not sure but, IIRC, it's some kind of bug

[B.Y.O.B.]

Have observed similar behavior before, issues when Camera or lights are positioned on XYZ (0,0,0), so i checked coordinates.
Then, after another change: Spot Light moved on X to 0.01, all went smooth.

Nice find, this is most likely the cause.
It's probably a bug triggered by numerical precision issues.
In general it is a bad idea to place stuff exactly at the world origin (in any renderer).

The Nvidia OpenCL compiler seems to make the problem more likely.