PRT Ember streaking

Deprecated Ember Bug Reports
1

StreakyEmber.JPG

Alpha 2, 2012

The apple is made with PRT Ember, the box is geometry verts. There’s streaking in the PRT Ember along the X axis (world and object are aligned). This PRT Ember is basically Input:Position -> TexmapEval -> Density. The TexmapEval is reading in a 3D map in object space.

EDIT: If I don’t use PCache, the streaks are random. Each time I render, even if I change nothing else, the streaks move. And sometimes there’s a non-streaky set of points that is transformed incorrectly. See below…

StreakyEmber2.JPG
StreakyEmber3.JPG

The camera was swung around, so in both images the streaks are still along X, but the non-streaky copy is offset.

2

StreakyEmber4.JPG

So this is shot from so the camera is looking -Z. The streaks are still in X. But the non-streaky offset apple is rotated. It’s actually what the apple would look like if you looked at it from the +X side.

3

Jitter in the PRT Ember doesn’t affect it other than reducing moire along Y and Z.

4

StreakyEmber5.JPG
StreakyEmber5.JPG1429×513 75 KB

Here it is with Cellular. Notice that in the viewport you have just a few blobs, but in the render there are more, and only some have streaks.

5

Can you upload the scene file with the Cellular?
I made my Cellular and did not see the issue.

EDIT: I was able to repro this, it is in fact random. Seems to happen every SECOND time I hit the render button, or when I rotate the view. I suspect the texmap eval. is seeing ghosts :slight_smile:
Also if I check PCache, the bad pattern persists, so it is obviously wrong Positions sent to Krakatoa, thus an Ember problem and not a Krakatoa one. Just in case there was any doubt…

We will look into it.