Hi Everyone,

I've found an odd issue while rendering an animation of a plain flat surface with displacement mapping applied. 

The shading of the extruded sides of the object are inconsistent if the object or camera moves.  I was expecting this to be consistent but obviously that is not the case.

Can someone elaborate as to why this is?

Kind regards,
                            CG

Some sample renders showing the problem would help.

Attached Link: 900k avi showing odd shading with displacement mapping

Note the sides of the extrusion that jump between medium and light gold, height definition is maintained, but the sides display some odd shading artifacts.  Any clues as to how to keep this from happening?

Thanks,
                   CG

Given that there are rapid changes in the displacement, I'd try lowering the shading rate (and for P6 turn off Texture Filtering, for P7 set to None on the displacement image).
I'd also check the "Normals_Forward" box.

One final thought is that if your using Depth Mapped shadows, increase the Map size or switch to Raytraced shadows (remember to adjust the bias as well).

Very cool that you replied.  I'll try those out and post my results.

Thanks,
                  CG

OK so I had some time to look into this, implementing the changes recomended, didn't help unfortunately.  This may be a result of the plane primitive not having any y depth (seems plausible).  To recap, the problem generally works like this:

1.  Create an image in photoshop of several squares overlapping each other (make sure each square is a diffrent shade of solid grayscale, e.g dark-grey, medium-grey, light-grey,...etc.

2.  Save the image as a bitmap (.bmp) file

2.  Launch poser and load the flat, single-sided primitive (from props->primitives-single-sided plane)

3.  Go to the default material for the one-sided primitive and connect a 2d image node to the displacement attribute.  Specify the bitmap you just created.  Set displacement attribute to .08

1. Create a 640x480, 300 frame animation of the main camera trucking in towards the flat plane from the side or a 45 degree angle so as to be able to see the y angle of the render (e.g. keyframe 0: flat plane fills half of the screen, keyframe 300: flat plane fills 3/4 of the screen)

5.  Render using firefly with displacement enabled

Result: Displacement height is correct, however the sides of the object display odd shading artifacts over time.

I can't remember where I read this now, but I understand that firefly just plain old doesn't like displacements in animations.  It recalculates the shadows at every frame and does so without consistency.  There is no known way around it from what I understand.

This shadow issue isn't only in firefly from what I remember reading aswell.  A number of rendering engines have similiar problems.  I think Carrara tries to get around it by allowing you to select for it to only calculate shadows once, but if your camera angle or light source changes, it will again have these troubles.

If I can find more indepth info on it I'll post a link.  It is really a huge let down.  It isn't relegated only to displacement maps, either.  A lot of shader node stuff has known bugs like that when used for animation.  It drives me insane!!

I agree, proper displacement mapping would provide a very fast solution to potentially complex projects.  I'll send the project file to e-frontier and see what they say about it.

Ciao.