Renderman has in recent versions used a combination of micropolygon and raytracing. So for things directly seen by the camera micropolygon rendering was used. But if those things needed indirect lighting, reflections and so on then raytracing was also used, as part of shading.
In some circumstances using micropolygon rendering speeds things up, particularly if there is heavy motion blur.
Micropolygon, and PBR micropolygon in Houdini use a similar technique.
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Technical Discussion » Some questions about rendering (Mantra)
- pwquint
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Technical Discussion » Some questions about rendering (Mantra)
- pwquint
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Setting light samples to 50, that sounds like a really old tutorial from two or three versions of Houdini ago - if you can let me know which tutorial you saw that in I'll add a comment on vimeo.
I think the word raytracing is being used in a couple of different ways here. Of course PBR shoots rays and so uses raytracing. One of the alternative rendering engines in Houdini is also called ‘raytracing’. PBR itself comes in two flavours a raytracing mode and a micropolygon mode.
In general PBR-Raytracing is the best choice for everything. There is a good explanation of the topic here:
http://www.sidefx.com/docs/houdini12.5/render/understanding [sidefx.com]
I think the word raytracing is being used in a couple of different ways here. Of course PBR shoots rays and so uses raytracing. One of the alternative rendering engines in Houdini is also called ‘raytracing’. PBR itself comes in two flavours a raytracing mode and a micropolygon mode.
In general PBR-Raytracing is the best choice for everything. There is a good explanation of the topic here:
http://www.sidefx.com/docs/houdini12.5/render/understanding [sidefx.com]
Technical Discussion » Integer Frame Motion Blur
- pwquint
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I believe there is a control on the motion blur settings of the Mantra ROP to determine if motion blur is trailing, leading or centred (I don't have Houdini right now). If you set it to trailing, with a shutter time set to 1, you should get motion blur for the full frame.
Technical Discussion » Integer Frame Motion Blur
- pwquint
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Not sure if matching motion blurs works, and also not sure that I understand your question. But the shutter time parameter on the camera node controls how much motion blur there is. Set this to 1 and you will get a full frame's worth of motion blur.
Best wishes
Peter
Best wishes
Peter
Technical Discussion » Multiple Sprites randomly applied to particle system.
- pwquint
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There are two components to rendering sprites - there is the Mantra Sprite Procedural which sets up the sprite geometry on each particle at render time, and there is the sprite shader which controls how they are shaded.
You can use attributes on your particles to override the texture settings on the sprite shader. You need to name the attributes identically to the sprite shop shader parameters, and then make sure they are being transferred to the sprite - there is a parameter on the sprite procedural that controls which attributes get transferred.
Creating attributes on your particles you can either randomise the attributes using for example an expression like floor(rand($PT) * 10) or if you need a limited number of varients then you can use the group pop to divide your particles randomly into say five groups and then set different attriutes on each group.
Peter
You can use attributes on your particles to override the texture settings on the sprite shader. You need to name the attributes identically to the sprite shop shader parameters, and then make sure they are being transferred to the sprite - there is a parameter on the sprite procedural that controls which attributes get transferred.
Creating attributes on your particles you can either randomise the attributes using for example an expression like floor(rand($PT) * 10) or if you need a limited number of varients then you can use the group pop to divide your particles randomly into say five groups and then set different attriutes on each group.
Peter
Technical Discussion » material that emits light
- pwquint
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A constant material will ‘emit’ light if you crank up the colour values enough (and make sure you are using PBR).
Technical Discussion » Maintaining UV on fluid
- pwquint
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As far as I know this is not straightforward, as you will get a problem with seams in your polygonised geometry - compare a sphere that has uvs applied as point attributes to one that has them applied as vertex attributes. The former will have a very clear seam. The fluid surface node is going to convert point uv values on your particles to point uv attributes on the polygonal mesh. So you will get a seam.
It may be that there is an elegant solution to this, but I've not yet come across it. If your fluid is highly viscous, and essentially a single blob, you may be able to shrink wrap a surface that has good uvs around your fluid using a ray sop. Alternatively (and this appears to be the method used in some of the empolygonizer examples) you can use a procedural texture that accepts 3d point data then you simply use a rest coordinate on your fluid particles and transfer this to your fluid surface. If all you need is some noise (such as for lava), or a marble like texture this will be fine.
If you want a texture image it won't work, and you'll be forced to use the uv method and hope the seam can be hidden. In the empolygonizer case they seem to be treating the liquids as a flat object in uv terms - I'm guessing with the u values repeating as more and more fluid is emitted. In that case the seam issue won't be apparent, but if your fluid flow is more cylindrical - water from a tap for example - it may look odd.
But perhaps someone else has found a good way to approach this.
It may be that there is an elegant solution to this, but I've not yet come across it. If your fluid is highly viscous, and essentially a single blob, you may be able to shrink wrap a surface that has good uvs around your fluid using a ray sop. Alternatively (and this appears to be the method used in some of the empolygonizer examples) you can use a procedural texture that accepts 3d point data then you simply use a rest coordinate on your fluid particles and transfer this to your fluid surface. If all you need is some noise (such as for lava), or a marble like texture this will be fine.
If you want a texture image it won't work, and you'll be forced to use the uv method and hope the seam can be hidden. In the empolygonizer case they seem to be treating the liquids as a flat object in uv terms - I'm guessing with the u values repeating as more and more fluid is emitted. In that case the seam issue won't be apparent, but if your fluid flow is more cylindrical - water from a tap for example - it may look odd.
But perhaps someone else has found a good way to approach this.
Houdini Learning Materials » Short Tutorial on the Ray SOP
- pwquint
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I've uploaded a short tutorial on the Ray SOP.
A look at some uses for the Ray SOP - a SOP that allows you to project the points of one object onto the surface of another. In this video we look at four uses for the SOP - to transform the shape of one object to match another, to detect when one object is below another, and to transfer UV attributes from one object to another. Finally we look at how to use the Ray SOP to project some ‘ivy’ geometry onto a pillar.
https://vimeo.com/60937947 [vimeo.com]
I attach the project files.
Hope it is useful.
A look at some uses for the Ray SOP - a SOP that allows you to project the points of one object onto the surface of another. In this video we look at four uses for the SOP - to transform the shape of one object to match another, to detect when one object is below another, and to transfer UV attributes from one object to another. Finally we look at how to use the Ray SOP to project some ‘ivy’ geometry onto a pillar.
https://vimeo.com/60937947 [vimeo.com]
I attach the project files.
Hope it is useful.
Houdini Learning Materials » Layered Shaders
- pwquint
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The Layer SOP simply allows you to create two or more sets of attributes on a surface. It does not of itself allow you to place two materials.
I don't work with Nurbs that much, but I think that the carve sop works by using trimcurves, so even after the carve you will have just one primitive. You will therefore get just one shader. If you convert the result to polygons and create two different primitive groups, then the material sop should work.
I don't work with Nurbs that much, but I think that the carve sop works by using trimcurves, so even after the carve you will have just one primitive. You will therefore get just one shader. If you convert the result to polygons and create two different primitive groups, then the material sop should work.
Houdini Learning Materials » Layered Shaders
- pwquint
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Yes you need to create your own VOPs shader to take advantage of multiple layered textures. Make sure, however, that that is really what you need to do. If you write a shader that combines different textures at render time then the calculations for combining the textures will be done for every single sample. It may be more efficient to, e.g. combine the textures in COPs. You can usually achieve a great deal by good use of the colour, reflectivity maps.
If your model is polygonal and you want different materials on different parts you can use the material sop to give each part different materials, or material parameters.
A case where this won't work is, for example, where one of your texture components is procedural and based on point coordinates - a 3D noise function, for example. In that case you will need to build your own shader. The tutorial I did on materials in H11 gives some examples of doing this.
If your model is polygonal and you want different materials on different parts you can use the material sop to give each part different materials, or material parameters.
A case where this won't work is, for example, where one of your texture components is procedural and based on point coordinates - a 3D noise function, for example. In that case you will need to build your own shader. The tutorial I did on materials in H11 gives some examples of doing this.
Houdini Learning Materials » Loop Flame Tutorial
- pwquint
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As explained in my earlier post I am going to start posting links to my tutorials here, together with the project files. I know some people can access this forum, but not google sites or vimeo, so at least this way they will get the files.
This tutorial has been out for several months - it looks at the way to generate a flame that loops seemlessly - allowing you to render a limited number of frames and yet have a flame that appears to burn continuosly.
The tutorial is at https://vimeo.com/46910933 [vimeo.com]
I attach the scene file.
Peter
PQHoudini Tutorial http://vimeo.com/channels/5410 [vimeo.com]
This tutorial has been out for several months - it looks at the way to generate a flame that loops seemlessly - allowing you to render a limited number of frames and yet have a flame that appears to burn continuosly.
The tutorial is at https://vimeo.com/46910933 [vimeo.com]
I attach the scene file.
Peter
PQHoudini Tutorial http://vimeo.com/channels/5410 [vimeo.com]
Houdini Learning Materials » Passes in H12
- pwquint
- 53 posts
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As explained in my earlier post I am going to start posting links to my tutorials here, together with the project files. I know some people can access this forum, but not google sites or vimeo, so at least this way they will get the files.
This tutorial has been out for several months - it looks at the way to generate and then composite passes in H12.
The tutorial is at http://vimeo.com/48977445 [vimeo.com]
I attach the scene file.
Peter
PQHoudini Tutorial http://vimeo.com/channels/5410 [vimeo.com]
This tutorial has been out for several months - it looks at the way to generate and then composite passes in H12.
The tutorial is at http://vimeo.com/48977445 [vimeo.com]
I attach the scene file.
Peter
PQHoudini Tutorial http://vimeo.com/channels/5410 [vimeo.com]
Houdini Learning Materials » Dynamic Wetmaps Tutorial
- pwquint
- 53 posts
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As I mentioned in my earlier post I am going to start posting links to my tutorials here, together with the project files. Some people can access this forum, but not google sites or vimeo, so at least this way they will get the files.
This tutorial has been out for a month or so. It looks at a technique for generating wetmaps in Houdini.
The tutorial is at http://vimeo.com/52290971 [vimeo.com]
I attach the scene file. Enjoy
Peter
PQHoudini Tutorial http://vimeo.com/channels/5410 [vimeo.com]
This tutorial has been out for a month or so. It looks at a technique for generating wetmaps in Houdini.
The tutorial is at http://vimeo.com/52290971 [vimeo.com]
I attach the scene file. Enjoy
Peter
PQHoudini Tutorial http://vimeo.com/channels/5410 [vimeo.com]
Houdini Learning Materials » Flip Fluids in Houdini 12
- pwquint
- 53 posts
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I am going to start posting links to my tutorials here, together with the project files. I know some people can access this forum, but not google sites or vimeo, so at least this way they will get the files.
This tutorial isn't really an introduction to Flip fluids - the Masterclass on this website already gives a brilliant introduction, but this video does look at some of the new workflows in H12.
The tutorial is at Vimeo http://vimeo.com/55764137 [vimeo.com]
This is the first part - there are two other parts which you can find on Vimeo - for example by going to the tutorial channel through the link below.
I attach the scene file.
Peter
PQHoudini Tutorial http://vimeo.com/channels/5410 [vimeo.com]
This tutorial isn't really an introduction to Flip fluids - the Masterclass on this website already gives a brilliant introduction, but this video does look at some of the new workflows in H12.
The tutorial is at Vimeo http://vimeo.com/55764137 [vimeo.com]
This is the first part - there are two other parts which you can find on Vimeo - for example by going to the tutorial channel through the link below.
I attach the scene file.
Peter
PQHoudini Tutorial http://vimeo.com/channels/5410 [vimeo.com]
Technical Discussion » glass material problem
- pwquint
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It looks like an index of refraction problem to me. The outside ior should be set to 1 the inside IOR to something like 1.3 on the glass material. You also might want to enable Fresnel, I think the shader turns it off by default. If you are still having problems do post a version of your scene file.
Houdini Indie and Apprentice » can houdini read footage?
- pwquint
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Houdini, including COPs can only read a sequence of image files, not a movie. So you need convert your AVI / MP4 or whatever into a sequence: image.001.jpg, image.002.jpg and so on. A video editor such as Sony Vegas allows you to render to an image sequence, or you can use ffmpeg to covert your file into a image sequence. You can then use e.g. a file node in COPs with the filename set to image.$F3.jpg for example to bring in the successive frames.
Technical Discussion » I have a problem houdini12 fluid emission rate
- pwquint
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At some point Sidefx were going to reach an arrangement to put my videos up on a Chinese site. I guess that hasn't happened. If there is an easy way to make them available in China I'd be happy to look at it.
Technical Discussion » Volumetric Rainbow
- pwquint
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This isn't that straighforward. Firstly the default smoke (volume) shaders deal with reflected not emitted light. For your rainbow to emit light you need to use something like the flames shader, which allows you to emit light from a volume. I've converted it to do this in the attached file. You need to convert all the fields to say density rather than temperature etc. and you need to set the color ramp to white, and then enable tint with point colour.
Secondly you need to use PBR rendering and on the shading tab make sure the diffuse limit is 1 or more. To increase quality increase max ray samples on the sampling tab, and if necessary decrease the noise level.
Secondly you need to use PBR rendering and on the shading tab make sure the diffuse limit is 1 or more. To increase quality increase max ray samples on the sampling tab, and if necessary decrease the noise level.
Technical Discussion » flip solver and velocity source question
- pwquint
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Check out the pump shelf tool - this allows you to set up a source that just affects velocity without emitting new particles.
Technical Discussion » Shadow matte not working (with file)
- pwquint
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I've not seen the tutorial, but the shadow matte is doing what it should in this file. Shadowmatte material sets the alpha channel, only, of your render. You probably don't want your sphere to show up in the render, so you might want to ensure this is rendered as a phantom (look at the render tab of the Geometry node).
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