Morning everyone,

been wrestling this problem related displacement in Mantra Surface.
Here's the rendered video to illustrate it better,

http://www.youtube.com/watch?v=rUCckMSx80A [youtube.com]
http://www.youtube.com/watch?v=RBQCpN0SLhI&feature=mfu_in_order&list=UL [youtube.com]

The displacement on the rocks seem to be either static or animated. With little hope as the rocks are not deforming geometries, i tried appending “Rest Position SOP” suggested by my mentor. No good.

Thought it might be due to displace based on World/Object Space, had no improvement.

Maybe they were being animated for turntable so i removed the keyframes on the objects and animated a camera instead, did not do any good too.

Threw in a default “Mantra Surface” shader and enabled noise caused the same effect while “Displacement” Shader in Material Palette rendered correctly.

Encountered similar situation in another 3D application, the shader required a reference point in order to work correctly. Unfortunately, i have no idea how to do that here.

Don't have the hip file with me atm, will attach it asap.
Will be grateful if somebody is willing to point me to a solution.

eitht.

Rest Position is the key.

Your displacement shander needs to have the Rest Position VOP in it in place of P in to the position to whatever procedural noise you are using. Same goes for the surface shader.

The Rest SOP is used to create the alternate “static” point position. Where you put this rest in the chain is key. It has to be before any deformation is happening on your object.

The key test to see that your rest attribute is in fact static is to put a Point SOP at the bottom of your geometry and put $RESTX , $RESTY and $RESTZ in place of $TX , $TY and $TZ for position and see if your geometry animates over time. If it does, your rest attribute needs more work.

Sometimes all it takes is a Time Shift SOP set to frame 1 in to the second input of your Rest SOP if you really need to save your scene. Proper method should have the Rest SOP right after the initial construction of the geoemtry before you apply any deformations (Transform SOP, Copy SOP, etc.).

Woo, thank you!

Fixed it, http://www.youtube.com/watch?v=bR3CtWgeEIg [youtube.com]

Had no idea Transform and Copy SOP were categorized under deformations, thought deformation meant surface deforming (e.g. blending shapes).

By default, it is set to camera space which caused displacement to animate. Texture, Object, World space will fix it, i tested all 3 types but World space doesn't work unless I misunderstood.

Placed a Rest SOP right after the Sphere and appended Point SOP at the end with $REST expressions, the displacement still animated. Fed Timeshift SOP and same problem persisted. To be honest, i followed step by step but did not understand it.

Still waiting for a chance to get someone in my school to explain to me as i felt a little ashamed to ask here again (Hence the slow reply). Mmm… is it possible to explain the Rest Position SOP and Timeshift SOP part in a simpler manner or is this the simplest? ><

eitht

Hello,

wanted to share this with anybody who needed it.
Had my lecturer Mr Ron explain a little more so thanks to him.

eitht.