There aren't any pointers aside from “more samples.” I've found in testing the diffusion based PBRSSS takes between 300 and 6000 samples to converge to a low amount of noise, depending on scatter distance. I'm not sure why you are getting flickering, perhaps sample bias accumulating through the refraction bounces? Increasing pixel samples may help.
Expect long render times for high resolution low-noise images. The old shader based sss is an option some turn to, but you really lose out on a lot of important features for production such as variance anti-aliasing and per-light aovs. The quality of the old algorithm left a lot to be desired.
Some turn to uniform volume, but I would expect pretty decent render times there as well.
Edit:
this was a 47 minute render with principled shader for milk and glass. There are some odd color shifts happening in the glass, as well as sample bias patterns in the noise.
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Technical Discussion » Milk Material with SSS?
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- jsmack
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Technical Discussion » Nvidia RTX
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- jsmack
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The RTX series have hardware for acceleration of BVH generation and intersection. Nvidia claims 6x speed compared to the software approach required in previous generations. Whether this is achieved by production renderers remains to be seen. Raytracing is likely to see more than the incremental “generation speedbump” increase that is seen in compute/shading/gaming usage. Perhaps the bottleneck just moves elsewhere and we do only see marginal (less than 2x) gains.
Edited by jsmack - yesterday 21:55:13
Technical Discussion » Vex luminance function
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- jsmack
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I think houdini is using NTSC primaries for legacy reasons. Houdini is based on the 1980's precursor Prisms, which was used heavily in NTSC broadcast graphics.
Technical Discussion » Instancing Objects Orienting to poly Normal but need to add control to blend orientation to scene Y up.
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- jsmack
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slerp() is for quaternions, if you want to build the full orientations for both the y-up and N-up cases, you can use slerp to blend between them using some blend value (0-1).
However, if you want to blend just the up vector from the normal to Y axis, you can use lerp function or mix VOP and normalize the result. Then output the resulting blended vector as your up axis.
However, if you want to blend just the up vector from the normal to Y axis, you can use lerp function or mix VOP and normalize the result. Then output the resulting blended vector as your up axis.
Houdini Indie and Apprentice » Why the double "=" in if statement (if @P == 2)
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- jsmack
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Group syntax accepts either form for comparisons. Because assignments don't make sense in this context, it can be assumed that the symbol is always refers to a comparison for terseness.
Technical Discussion » COPS Periodic noise?
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- jsmack
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I think all the same noises are available in every context. The VOPCOP generator and filter let you build a shader with familiar VOPs.
Houdini Indie and Apprentice » Point color won't get used by Principled Shader when bump is used
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- jsmack
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There are a couple issues with the way your shader network is constructed. I have attached a scene file with an alternative build.
Houdini Indie and Apprentice » textport and VEXpression help
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- jsmack
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Unfortunately, yes. I usually hit F1 when the cursor is over the function name in question. The hotkey opens the help brower to the function's documentation.
Houdini Indie and Apprentice » Export each by connectivity
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- jsmack
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I would use the frame number to switch between each mesh, and export as an animation.
Why do you need each one in a different file? Modern workflows generally avoid file instancing like that. Also keep in mind instancing millions copies of some very light mesh will be much slower than rendering a big dense mesh, or fewer instances of some not-so-light meshes.
Why do you need each one in a different file? Modern workflows generally avoid file instancing like that. Also keep in mind instancing millions copies of some very light mesh will be much slower than rendering a big dense mesh, or fewer instances of some not-so-light meshes.
Technical Discussion » Vex luminance function
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- jsmack
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Its the dot product with the tristimulous values.
Your looking at the wrong definition of luminance:
https://en.wikipedia.org/wiki/Relative_luminance [en.wikipedia.org]
Your looking at the wrong definition of luminance:
https://en.wikipedia.org/wiki/Relative_luminance [en.wikipedia.org]
Edited by jsmack - Sept. 18, 2018 17:42:22
Houdini Lounge » will there be a live stream for H17 Launch Event
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- jsmack
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Technical Discussion » Transform node
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- jsmack
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I think you may be able to achieve what you need with a primitive SOP.
It transforms in the local space of each face.
It transforms in the local space of each face.
Technical Discussion » Random POP colors
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- jsmack
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On the source, give a name to the ‘born group’. Then set the color on the born group with your desired method (I think there is a color pop). Use a random function with the current frame as the seed, and either use it directly for rgb, or look up in a color ramp with some pre-selected colors works well to avoid the ‘rand rgb’ look.
Technical Discussion » Projecting vertical noise around a tube like object
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- jsmack
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Use cylindrical coordinates.
pos = @P - center;
theta = atan2(pos.z,pos.x);
h = pos.y;
r = length(pos-dot(pos,{0,1,0})*{0,1,0});
uv = set(theta,h,r);
You might need to blend two noises with opposite seams to eliminate the seam where theta goes from -PI to PI.
pos = @P - center;
theta = atan2(pos.z,pos.x);
h = pos.y;
r = length(pos-dot(pos,{0,1,0})*{0,1,0});
uv = set(theta,h,r);
You might need to blend two noises with opposite seams to eliminate the seam where theta goes from -PI to PI.
Technical Discussion » How can I manipulate a point/edge/primitave in world space?
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- jsmack
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There's no way to access the data like that with move tools; edit/transform tools work as deltas, they don't know anything about the location of the current point. Curious, what does that dialog put in for absolute position if there are multiple points selected?
The geometry spreadsheet allows keying in point positions directly, but its not recommended, as it locks the geometry to your scene file.
You might be able to hack the edit tool by dragging a point to the origin, committing the edit, and then snapping it back to the previous position using a template. Then the translate values will represent the absolute position.
The geometry spreadsheet allows keying in point positions directly, but its not recommended, as it locks the geometry to your scene file.
You might be able to hack the edit tool by dragging a point to the origin, committing the edit, and then snapping it back to the previous position using a template. Then the translate values will represent the absolute position.
Edited by jsmack - Sept. 15, 2018 04:20:39
Houdini Indie and Apprentice » How to rotate on scattered geos on Y axis (@N with @up ??)
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- jsmack
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If you are lazy like me, you can use an orient attribute to align them and attribute randomize to pick the angle.
Attribute randomize:
name: theta
distribution: Uniform
dimensions: 1
min value: 0.0
max value: 1.0
Then use an attribute wrangle to create a quaternion:
or if Eulers with degrees are more your thing:
Attribute randomize:
name: theta
distribution: Uniform
dimensions: 1
min value: 0.0
max value: 1.0
Then use an attribute wrangle to create a quaternion:
float u = @theta * M_PI; @orient = set(0, sin(u), 0, cos(u));
or if Eulers with degrees are more your thing:
vector rot = set(0, 360*@theta, 0); @orient = eulertoquaternion(radians(rot), 0);
Technical Discussion » How can I manipulate a point/edge/primitave in world space?
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- jsmack
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Have you tried switching the handle from component mode to world mode?
Hit the ‘m’ key to cycle through the options, or right-click the handle and select “Align Handle->World”.
Hit the ‘m’ key to cycle through the options, or right-click the handle and select “Align Handle->World”.
Technical Discussion » Multiple UVs
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- jsmack
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Multiple UV workflow was reworked recently. Most UV operations have a string field to enter an arbitrary name for the uv set. Use the same name in multiple operations to modify the same set. Enter a different name to create/modify an alternate uv set.
Technical Discussion » camera property: cropmask, how does it work?
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- jsmack
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Technical Discussion » OCIO Implementation plan
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- jsmack
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twod
The next major version of Houdini has some improvements to the OCIO workflow
Will there be support in scene viewers and ocio displays with looks? When flipbooking/opengl rop is used, there currently isn't any control over the display used. Will this be controllable in the future? In the past I have had to disable OCIO in order to flipbook in controllable way, resorting to external software to apply the look and transform from linear to the display space.
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