Motion Blur on procedural texture

[thibh]

Hi guys,

We have a strange problem in Houdini with our shading. We're using procedural textures for the terrain shading (the green noise pattern) but it doesn't seem to receive any motion blur.

You can see the road and the mud having correct motion blur due to them being textures, but not the procedural textures.

Do you have any idea why this is happening?

Thanks for your help!

 

[gui]

can u share some file?

are you using rest attribute in vops? is the texture sliding?

[thibh]

We do use a rest attribute and the texture isn't sliding.

 

My file only contains digital assets so it might be difficult to share it.
I'll make you a file with only the shading when I have some free time. Thanks for your help =) !

 

[gui]

what type of motion blur are u using? Can u send a screen shot of the mantra render settings and perhaps, the texture part of the shader?

Edited September 30, 2015 by gui

[fathom]

looks like you're generating noise in camera space.  you sure the rest position is coming thru okay?  take your rest position and export it as a deep raster and see if it has the values you'd be expecting.

[TheDude]

Make sure your rest position is also in worldspace when you pull it in. I haven't tried, but I wonder if you force your rest position into the noise, but also link it to camera space, that your texture will stick onto geo correctly, but not be affected by motion blur with camera movement... Haven't tried it, but could be what's happening?

[thibh]

The rest position were all set on "space:object", I tried to switch them all to "space:world" but it doesn't seem to make any difference unfortunately.

[gui]

again: can u tell the mantra settings?? what type of motion blur are u using? It´s difficult to help u if u don´t provide us with any info.

[thibh]

Sorry for the late reply about the settings, I was just about to post them, I was busy.

Here are the main settings of my mantra node.

Thanks again for your help!
 

Edited September 30, 2015 by thibh

[gui]

do u have "velocity motion blur" in the geometry (with the texture) toggled on?

[thibh]

do u have "velocity motion blur" in the geometry (with the texture) toggled on?

 

I am object merging the terrain on a geo node and the velocity motion blur is toggled on on the geometry node where the terrain is imported.

[gui]

try to toggle it off. Probably the geo don´t have velocity, so it won´t have motion blur.

[thibh]

try to toggle it off. Probably the geo don´t have velocity, so it won´t have motion blur.

 

When I toggle it off the the image texture (the mud close to the road) doesn't have motion blur any more. So it seems to be correctly affecting the terrain for the image texture, but not for the procedural ones.

[fathom]

The rest position were all set on "space:object", I tried to switch them all to "space:world" but it doesn't seem to make any difference unfortunately.

 

wait.  are you referring to the rest position vop in your shader?  that's not assigning the rest position, that's importing the rest position from the geometry if it exists.  if it DOESN'T exist, it will then pull in the global shader space P (or whatever point you plug into it) and transform that into the space you indicate in the vop.  frankly, that should work for your case unless you're specifically defeating it by using Get Blur P somewhere.

[fathom]

describe your animation setup.  you mentioned object merging.  what is moving in your scene?  the camera or the geo?  in your viewport, presumably you've verified that your mountain is in fact moving, right?

[thibh]

It seems to work, I was not aware that you needed a rest pos at the sop level too, I only had a rest pos in my vop shader.

The only thing now is that it looks like the procedural texture has changed scale because of the rest pos in sop but the motion blur is working and I guess I'll just have to get the scale correct.

I'll let you know if everything works, thanks a lot for your help!!

[fathom]

still, i think there's something else at work here.  i think it's your object merge.  the rest position stuff shouldn't matter unless your object is actually deforming, which it shouldn't be -- unless it's being merged into a geometry that's moving.

[thibh]

In fact we're cheating the car move in the scene by leaving the car at the center of the world and moving the terrain underneath. So I have a null which is animated, and I attached my geometry with my object merged terrain inside to the null.

[fathom]

can you snap an image of your network layout and your object merge parms?

 

any reason your don't just attach your terrain object to the null object to animate it?  why merge it into another object?

[thibh]

can you snap an image of your network layout and your object merge parms?

 

any reason your don't just attach your terrain object to the null object to animate it?  why merge it into another object?

 

We are using a digital asset workflow so that one artist can work on the terrain modeling / shading while another one can place it on the layout and do other stuff with it on another scene.

 

This is the node tree inside the digital asset, with the terrain coming from an obj file.

 

The shading is on another digital asset and is linked into the material node on this tree.

 

 

 

The scene controls is the animated null which is moving the terrain and everything on top of it (rocks, trees and so on).

 

 

This is the node tree inside the "layout_terrain" node, I'm just importing the terrain and doing some operations on it (flattening the road and so on).