I want to output arbitrary data through the diffuse pass of a mantra render. I can't have any antialiasing. Where are the knobs on mantra that control antialiasing so I can turn it off?
Thank you!
-Greg
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Technical Discussion » Turn off antialiasing in mantra
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- grhart
- 21 posts
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Technical Discussion » rotation between two vectors
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- grhart
- 21 posts
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Technical Discussion » rotation between two vectors
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- grhart
- 21 posts
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I must not be understanding something here. Why when I use this expression in the Z rotation channel of a transform SOP, does it return -45, when I am expecting it to return 90?
explodematrix(mlookat("“,”“), ”RST“, ”XYZ“, ”RZ")
I just want to rotate an object from one unit vector to another. Thanks for any tips!
explodematrix(mlookat("“,”“), ”RST“, ”XYZ“, ”RZ")
I just want to rotate an object from one unit vector to another. Thanks for any tips!
Technical Discussion » issue rendering Wireframe sop
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- grhart
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That fixes it. Thank you, Skybar.
So am I understanding right that the “Preview” checkbox in the H13 Render View invokes ray tracing while in H12.5 it does micro polygon (or obeys the ROP)?
Thanks again.
So am I understanding right that the “Preview” checkbox in the H13 Render View invokes ray tracing while in H12.5 it does micro polygon (or obeys the ROP)?
Thanks again.
Technical Discussion » issue rendering Wireframe sop
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- grhart
- 21 posts
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Thanks Adam. Were you able to try a mantra render? That's where I'm seeing the difference (attached).
Btw, I'm using H12.5.562 and H13.0.447 on Mac OS X 10.9.3.
Thanks for any clues.
Btw, I'm using H12.5.562 and H13.0.447 on Mac OS X 10.9.3.
Thanks for any clues.
Technical Discussion » issue rendering Wireframe sop
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- grhart
- 21 posts
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I have a mesh going into a Wireframe sop (see attached .hip). Since upgrading from H12.5 to H13, it is no longer rendering as expected. Do you happen to have a clue why?
It almost looks like the tubes are inside out. The Wireframe's “Wire Radius” is set to 0.0002. When I increase it by a factor of 10, the expected results start to creep back in. Anything greater than 0.02 looks as you would expect. It's not really feasible to scale my entire scene up for this issue.
Swapping the Wireframe sop for the PolyWire sop fixes it, but by default, generates much too heavy of a result.
Any ideas? Thanks in advance.
-Greg
It almost looks like the tubes are inside out. The Wireframe's “Wire Radius” is set to 0.0002. When I increase it by a factor of 10, the expected results start to creep back in. Anything greater than 0.02 looks as you would expect. It's not really feasible to scale my entire scene up for this issue.
Swapping the Wireframe sop for the PolyWire sop fixes it, but by default, generates much too heavy of a result.
Any ideas? Thanks in advance.
-Greg
Houdini Lounge » sweep sop and custom point attrs
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- grhart
- 21 posts
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Houdini Lounge » sweep sop and custom point attrs
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- grhart
- 21 posts
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Is it possible to pass a custom point attribute into the “Scale” property of the sweep sop? In other words, each point on my backbone curve has a ‘myScale’ attribute and I want each cross section geometry to be uniquely scaled according to myScale. Sample hip is attached.
Thanks for any help.
-Greg
Thanks for any help.
-Greg
Technical Discussion » Tetrahedral volume grids
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- grhart
- 21 posts
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For those knowledgeable in the HDK, does it support defining a new data type, a tetrahedral volume grid in this case (or an octree), writing other custom op's to manipulate the new type, all renderable in Mantra?
Thanks,
-Greg
Thanks,
-Greg
Houdini Lounge » Average a point attrib across multiple frames?
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- grhart
- 21 posts
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I'm currently doing this with a bloated network of attribCopy and point sops. Surely there's a better way. I need to compute the average of $VX of the same point across n number of frames. I've looked at pointavg(), but it averages an attribute across all points in the same geometry. Coming from Maya/MEL, I just want to write a loop. What's the best approach in Houdini?
Thank you for any tips.
Thank you for any tips.
Technical Discussion » Aliases and Variables... and hrender
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- grhart
- 21 posts
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I'm creating custom variables inside the `Aliases and Variables…` window in Houdini, which get saved in my current hip file. I've primarily been using custom string variables throughout my workflow in file SOP's and ROP's. Is it possible to somehow override these variables with an hrender command-line option? I need to be able to render the same hip file multiple times with varying properties.
Any tips or examples would be appreciated. Or maybe there's a better approach entirely. Thanks,
-Greg
Any tips or examples would be appreciated. Or maybe there's a better approach entirely. Thanks,
-Greg
Technical Discussion » Tetrahedral volume grids
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- grhart
- 21 posts
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I'm working with tetrahedral voxel grids outside of Houdini. I'm looking for some ideas on efficient ways of importing this data into Houdini for manipulation and eventual rendering in Mantra.
Currently, I convert each tetrahedron into four disconnected polygonal faces and bring them in as such. This allows me to interpolate along faces and convert it all to a high-res cartesian grid in Houdini with an attribTransfer. The workflow and results could be better.
I'm not aware of native Houdini support for tetrahedral voxel grids. Assume I know nothing about the HDK. Is it possible to develope a set of tools to import, visualize, manipulate and render such data without converting to square voxels?
or is there a better way? Thanks for sharing.
-Greg
Currently, I convert each tetrahedron into four disconnected polygonal faces and bring them in as such. This allows me to interpolate along faces and convert it all to a high-res cartesian grid in Houdini with an attribTransfer. The workflow and results could be better.
I'm not aware of native Houdini support for tetrahedral voxel grids. Assume I know nothing about the HDK. Is it possible to develope a set of tools to import, visualize, manipulate and render such data without converting to square voxels?
or is there a better way? Thanks for sharing.
-Greg
Edited by - Sept. 16, 2011 15:12:25
Houdini Indie and Apprentice » curved particle motion blur?
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- grhart
- 21 posts
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Thanks for the tip, Jesse. If I understood right, that fellow's solution requires oversampling a sim, which I can't do because I'm reading points from disc.
I've almost arrived at a solution, but need some help wrapping it up. Basically, I'm reading a point's previous, current and next frames and drawing a spline between them. My network looks something like this: TimeShift SOP to retrieve prev and next frames, Add SOP to connect points as poly, Fit SOP to convert it to nurbs, Carve SOP to trim to proper length. Two questions remain:
1) How can I drive opacity of my rendered curve by a point attr? In other words, I want to scale opacity of the rendered curved by length of velocity. Creating an “Alpha” point attr, doesn't seem to get read by my material.
2) Need some way to check if a previous or next frame exists for a particular particle id and if not, extrapolate one. Not sure which SOP to look for here.
Thanks for any tips.
I've almost arrived at a solution, but need some help wrapping it up. Basically, I'm reading a point's previous, current and next frames and drawing a spline between them. My network looks something like this: TimeShift SOP to retrieve prev and next frames, Add SOP to connect points as poly, Fit SOP to convert it to nurbs, Carve SOP to trim to proper length. Two questions remain:
1) How can I drive opacity of my rendered curve by a point attr? In other words, I want to scale opacity of the rendered curved by length of velocity. Creating an “Alpha” point attr, doesn't seem to get read by my material.
2) Need some way to check if a previous or next frame exists for a particular particle id and if not, extrapolate one. Not sure which SOP to look for here.
Thanks for any tips.
Houdini Indie and Apprentice » curved particle motion blur?
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- grhart
- 21 posts
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I'm reading points with velocity from disk at integer frames (i.e. no sub-frame data exists). Turning on ‘Geometry Velocity Blur’ on the object level gives me great LINEAR motion blur in mantra. Is there a built-in Houdini way of rendering CURVED motion blur, where the rendering considers more time-steps? Increasing the ‘Geo Time Samples’ on the mantra Sampling tab isn't doing it, as I had hoped.
Thanks for any tips.
Thanks for any tips.
Houdini Indie and Apprentice » mantra: thickness of a curve
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- grhart
- 21 posts
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Houdini Indie and Apprentice » mantra: thickness of a curve
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- grhart
- 21 posts
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I have a simple curve SOP, and was pleasantly surprised to learn that it renders in mantra without converting it to a tube or other. But where do I control its thickness?
Thanks,
-Greg
Thanks,
-Greg
Houdini Lounge » mantra: how to holdout semi-transparent objects?
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- grhart
- 21 posts
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Houdini newbie here. I have two semi-transparent objects that I want to holdout from each other in two separate render passes to be added back together later in compositing. How do I go about this in Houdini/mantra?
My first attempt was to add the holdout object to the “Forced Matte” parameter of the mantra node. Then it was to turn on “Matte Shading” on the holdout geometry sop. In both cases, the holdout object is 100% held out, when what I really want is it to be held out only to the amount of its alpha.
Thanks for any pointers,
-Greg
My first attempt was to add the holdout object to the “Forced Matte” parameter of the mantra node. Then it was to turn on “Matte Shading” on the holdout geometry sop. In both cases, the holdout object is 100% held out, when what I really want is it to be held out only to the amount of its alpha.
Thanks for any pointers,
-Greg
Houdini Indie and Apprentice » hrender from command line failing. Advice?
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- grhart
- 21 posts
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The advectbyvolumes node appears to be the root of my woes. Others are reporting issues as well: http://www.sidefx.com/index.php?option=com_forum&Itemid=172&page=viewtopic&t=17530 [sidefx.com]
Technical Discussion » Particle motion blur causes Mantra to freeze mid-frame
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- grhart
- 21 posts
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Hi Stevie.
I'm a year late to your post, but am also seeing my renders freeze on the advectbyvolumes POP. Did you arrive at any solution or workaround? Whether or not it's the culprit, my GUI freezes on the advectbyvolumes/velocity_source/transform_into_our_parents_space sub node.
I'm running Houdini Apprentice v11.0.547 on Mac OS X v10.6.4
Thanks.
-Greg
I'm a year late to your post, but am also seeing my renders freeze on the advectbyvolumes POP. Did you arrive at any solution or workaround? Whether or not it's the culprit, my GUI freezes on the advectbyvolumes/velocity_source/transform_into_our_parents_space sub node.
I'm running Houdini Apprentice v11.0.547 on Mac OS X v10.6.4
Thanks.
-Greg
Houdini Indie and Apprentice » hrender from command line failing. Advice?
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- grhart
- 21 posts
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I thought it was isolated to hrender and hbatch, but now mantra renders launched from the Houdini GUI are indefinitely stalling after some small number of frames.
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