9 replies to this topic

[Richey]

Hi guys,

I would like to know how to create a motion vector pass with houdini. I found two forum topics and this shader (http://www.sidefx.co...8&versionid=608) on the net they didn't work for me. Could someone please explain me how to create a motion vector shader/pass? That would be great, all the other passes work fine.

Thanks a lot!
Richey.

[sam.h]

Here is an example of getting the motion vector in screen space.

Note the "allow image motion blur" parm that i added to the mantra rop and turned off so that the output isn't blurred.

I dunno how much you know about shading so ask if anything doesn't make sense!

Attached Files

•  motionVectors.hip   104.71K   281 downloads

[Richey]

Thank you so much Sam, the shader works!!! I need it for an important project.

One last thing I would like to know: How can I save the shader as a vex variable - so that I can use the shader as a pass?

Richey

[sam.h]

Use a Parameter node to export the variable and set the export to 'always'

Attached an example using a basic surface and exporting a pass set ...

Attached Files

•  motionVectors2.hip   273.54K   301 downloads

[Richey]

You are the best Sam, thank you!

[Jimbo55]

Hi Sam,
  Can you show how to use the same setup but on the geometry level?  I've tried using your setup and realized that if I have anything animated on the geometry level, the vector pass doesn't work.

[Jimbo55]

Here is the Hip of what I am trying to attempt.

Attached Files

•  motionVectors2_experiment.hipnc   349.48K   62 downloads

[sam.h]

You will need to have "Geo Time Samples" on at least 2 on the mantra node to get deformation blur. Let me know if that doesn't work and I will have a closer look!

(You can also add Geo Time Samples to a single object if you don't want it as a global setting, add the setting to your object with the gear icon > edit rendering parameters)

[Jimbo55]

Sam, Thank you!  Wow, so simple.  That seems to have worked.

[huanqing2008]

thans for sharing your shader, can you please tell me how to use it in nuke for example?