View Full Version : Displacement Presample Problem

01 January 2007, 08:04 AM
Hi guys,

Im having a problem with displacement. What was working fine, is now not and i cant fix the problem.

The following is in the output editor when it works:

G 0.4 progr: opening texture V:/PROJECTS/GOKU/Maps/Dinosaur/1K/Trex_head_displacement.tga, for reading
IMG 0.4 progr: opening texture V:/PROJECTS/GOKU/Maps/Dinosaur/1K/Trex_arms_displacement.tga, for reading

IMG 0.4 progr: opening texture V:/PROJECTS/GOKU/Maps/Dinosaur/1K/Trex_legs_displacement.tga, for reading

IMG 0.4 progr: opening texture V:/PROJECTS/GOKU/Maps/Dinosaur/2K/Trex_body_displacement.tga, for reading

GAPM 0.4 progr: 2.6% displacement presampled for object BodyShape

GAPM 0.4 progr: 30.8% displacement presampled for object BodyShape

GAPM 0.4 progr: 58.4% displacement presampled for object BodyShape

GAPM 0.4 progr: 85.2% displacement presampled for object BodyShape

GAPM 0.4 info : created 944 tessellation jobs from object BodyShape in 9313.796 ms

RC 0.4 progr: computing camera volumes

This is fine. BUT now when i render the whole presampled section doesnt appear, and the object displaces, but at ridiculaously low quality. I have no idea what is happening. Is there anyway presampling might not calculate when doing displacement?

01 January 2007, 01:41 PM
i have no idea about this specific message. but what approach on the displacement do you use?

you might wanna check out zbrushcentral for the maya-zbrush displacement pipeline. theres should be some free pdf by scott spencer that describes a very good approach on displament in maya using mental ray. If MR is what you want to use.


01 January 2007, 09:16 PM
Nothing special at all.

I've used this method heaps of times before, but this time it just seems to skip the presample stages in the output editor. As I said it DOES displace the mesh, but at extremely low quality and only a tiny tiny amount.

As usual, all I am doing is this:

1. Create a displacememant approx node in the approximation editor
2. Create a displacement shader and plug the shader into the displacement slot in the SG

voila! IT normally works. I have done this many times and never had this problem.

I still cannot find the solution and it's driving me insane.

01 January 2007, 10:23 PM
Ok, so i have a very weird solution.

I create a sphere in the scene and assign one of the displaced shaders to the sphere. I then create a NEW approximation node on the sphere. I render and voila! The displacement now works on the sphere and the main object.

HOWEVER..I save the scene, close Maya and then reopen the scene. The displacement is broken again. To get the displacement to render properly again, i have to put in a new shpere, assign an existing displaced shader and cerate a new approximation node.

The problem is on multiple machines as well. I have to say after using Maya for years now this is the most bizarre problem I have ever encounted.

If anyone has ANY comments, I could really use the advice.

Thanks guys.

01 January 2007, 11:36 AM
very strange. i have never encountered that maya looses the connection when reloading the scene.

however i might add that maya does not always show the connection of the approximation, sometimes you need to delete the objects history in order to see it (and sometimes that doesnt help either).

question, does the old approx still show in the approxeditor? and if it does, can it be reconnected to the sphere (you should get an error message if theres one approx already connected).

from what i also learned from the pipelineguide at zbrushcentral, was to turn off "feature displacement", under the objects shape /displacement/feature displacement


01 January 2007, 01:25 PM
is the disp map 32 bit ?
how big is your model in relation to worldspace

restarting maya and IMPORT the OBJ again (not the maya model) and re-assign the aproximation node ..might help

it happend to me before..that the approximation got bad and the only way to fix it is to re-import the OBJ from Zbrus hand start all over

01 January 2007, 03:12 AM
Feature displacement is turned off.

My model is rather large. Will this matter?

I am using 32 bit textures.

I can't reimport the mesh as the character is rigged with anim and alot of history. I have to use this mesh. Very annoying. We have found a workaround, but a very messy one as stated before. Im going to have a dig around and see if there are any wacky connections with my approximation node.

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