Hi guys,
I'm trying to achieve a result of soil that coming up from the ground as characters stomp over it. I am specifically looking at soil/debris that clumps initially like a fluid but then goes off in a ballistic motion.
Thus far, I've been able to get that effect using a flip solver with a ballistic attribute in the override force.
However, I've not been able to figure out how to get the particles orientation/rotation to change with a torque force. I've tried setting a random orientation and some torque force with a pop torque in the “particle velocity” or the “sourcing” input of the flip solver but I've not been able to get the particles to rotate.
Anyone has had any experience trying to get rotation in their flip particles?
Found 30 posts.
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Technical Discussion » Flip solver and particle rotations
- iamnelsonlim
- 39 posts
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Technical Discussion » Packed primitive copy instancing and rotational motion blur
- iamnelsonlim
- 39 posts
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Thanks Mark!
This is exactly as you said.
It did not occur to me that I would not be getting some sort of interpolated subframe data with particles.
And that “hack” of passing orient through cd and uv to get timeblend to interpolate the data is wicked awesome! :wink:
This is exactly as you said.
It did not occur to me that I would not be getting some sort of interpolated subframe data with particles.
And that “hack” of passing orient through cd and uv to get timeblend to interpolate the data is wicked awesome! :wink:
Technical Discussion » Packed primitive copy instancing and rotational motion blur
- iamnelsonlim
- 39 posts
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Hi Mark,
I opened up your scene and noticed that the difference was that I was causing my rotations by using the orient attribute and not rotating it with a transform.
The reason is because I am using a particle system with a torque force to spin my instanced geometry around.
I find that by using a copy sop to instance the geometry onto the particles with packed primitives, rotational motion blur calculation looks wrong. especially for geometry samples >2.
If I used the copy sop on a set of points from a grid that are rotating via a vopsop that applies a sin function to the orient, rotational motion blur seems correct.
Finally if I take the same particles and I used either point instance procedural shader or a instance object, the rotational motion blur looks correct.
All of the images are done with a “geo time sample” of 6 unless otherwise stated. I've also disabled “Geometry Velocity Blur” on the Sampling tab of the objects that are rendered.
I'm not sure what causes the odd rotational motion blur here. Although I could have a quick fix by simply using an instance object instead of a copy sop.
I opened up your scene and noticed that the difference was that I was causing my rotations by using the orient attribute and not rotating it with a transform.
The reason is because I am using a particle system with a torque force to spin my instanced geometry around.
I find that by using a copy sop to instance the geometry onto the particles with packed primitives, rotational motion blur calculation looks wrong. especially for geometry samples >2.
If I used the copy sop on a set of points from a grid that are rotating via a vopsop that applies a sin function to the orient, rotational motion blur seems correct.
Finally if I take the same particles and I used either point instance procedural shader or a instance object, the rotational motion blur looks correct.
All of the images are done with a “geo time sample” of 6 unless otherwise stated. I've also disabled “Geometry Velocity Blur” on the Sampling tab of the objects that are rendered.
I'm not sure what causes the odd rotational motion blur here. Although I could have a quick fix by simply using an instance object instead of a copy sop.
Technical Discussion » Packed primitive copy instancing and rotational motion blur
- iamnelsonlim
- 39 posts
- Offline
PradeepBarua
Have turn on “Use Template Point Attributes” on attribute tab of copy sop?
Yes. I have “Use Template Point Attributes” turned on.
Technical Discussion » Packed primitive copy instancing and rotational motion blur
- iamnelsonlim
- 39 posts
- Offline
hi guys,
I've been trying to find out more about this but haven't found much information. I have a set of points that Are rotating with a torque force applied. I copy a set of grass blades onto the points and packed them using the copy sops option to pack geometry.
However, I can't seem to get rotational motion blur out of my grass blades. Seems that they are only being blurred along v. Does anyone know how to achieve this?
Thanks
Nelson
I've been trying to find out more about this but haven't found much information. I have a set of points that Are rotating with a torque force applied. I copy a set of grass blades onto the points and packed them using the copy sops option to pack geometry.
However, I can't seem to get rotational motion blur out of my grass blades. Seems that they are only being blurred along v. Does anyone know how to achieve this?
Thanks
Nelson
Technical Discussion » Motion Vectors in Nuke need large multiplier
- iamnelsonlim
- 39 posts
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Hi guys,
Has anyone tried exporting a motion vector pass from the sidefx included example on motion vectors? It can be found with the getBlurP node help card.
I notice that I needed to multiply the motion vector by 100x in Nuke in order to get motion blur lengths that look close to what it would be like if the image was rendered with motion blur.
In my other test cases I've sometimes had to multiply the motion vector by as much as 1500x before I get similar length motion blur.
I'm curious if this is to be expected? Is there a way to render out motion vectors that have more reasonable values?
I'm not good with the math on this, so if anyone wants to explain the logic and math behind exporting motion vectors, I'll also be really grateful to read up.
Thanks a lot!
Nelson
Has anyone tried exporting a motion vector pass from the sidefx included example on motion vectors? It can be found with the getBlurP node help card.
I notice that I needed to multiply the motion vector by 100x in Nuke in order to get motion blur lengths that look close to what it would be like if the image was rendered with motion blur.
In my other test cases I've sometimes had to multiply the motion vector by as much as 1500x before I get similar length motion blur.
I'm curious if this is to be expected? Is there a way to render out motion vectors that have more reasonable values?
I'm not good with the math on this, so if anyone wants to explain the logic and math behind exporting motion vectors, I'll also be really grateful to read up.
Thanks a lot!
Nelson
Houdini Lounge » isolating particles from the dop network.
- iamnelsonlim
- 39 posts
- Offline
Hi guys,
I was wondering what is the best way of exporting only dop particles from a dop sim?
I currently have collision geometry in the dop network with my dop particles. However, I would only like the resulting particles. At the moment, the RBD geometry is coming out form the dop network as well.
I have tried to isolate the particles by adding a pop group and then a delete node after the dop network to delete everything except what is defined in the pop group.
Is there a better way to do this?
Thanks!
I was wondering what is the best way of exporting only dop particles from a dop sim?
I currently have collision geometry in the dop network with my dop particles. However, I would only like the resulting particles. At the moment, the RBD geometry is coming out form the dop network as well.
I have tried to isolate the particles by adding a pop group and then a delete node after the dop network to delete everything except what is defined in the pop group.
Is there a better way to do this?
Thanks!
Houdini Indie and Apprentice » H13 - Popnet - Normals are not used as Velocity
- iamnelsonlim
- 39 posts
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I think it was changed for clarity. Since we are emitting based on velocity. It would be clearer if we simply specify the velocity is equals to the normal before emitting, if that's what we wanted. Admittedly, it was convenient in the past.
The other way is also simply to drop a point sop. Add velocity. And specify it to $NX, $NY, $NZ.
:wink:
The other way is also simply to drop a point sop. Add velocity. And specify it to $NX, $NY, $NZ.
:wink:
Technical Discussion » rendering stereo extra image planes
- iamnelsonlim
- 39 posts
- Offline
I'm wondering if this is a houdini bug?? I can't seem to get it to render stereo for separate channel files.
Technical Discussion » rendering stereo extra image planes
- iamnelsonlim
- 39 posts
- Offline
Hi guys,
I've got a stereo cam rig template which I separately hook up a left and right cam.
When I try to render, the Output Picture produces a left and right image.
But if I specify extra image planes and check “different filename” to specify the filename, Houdini does not seem to write out the left and right channel files.
Anyone knows how to get this to work? I would like my extra image planes to output as separate files.
I'm using houdini 11.0
Thanks!~
I've got a stereo cam rig template which I separately hook up a left and right cam.
When I try to render, the Output Picture produces a left and right image.
But if I specify extra image planes and check “different filename” to specify the filename, Houdini does not seem to write out the left and right channel files.
Anyone knows how to get this to work? I would like my extra image planes to output as separate files.
I'm using houdini 11.0
Thanks!~
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