Hey Henster, where should I use Ng instead of N?
The only place where I use N is in the SEM shader, but I think changing this to Ng won't make any difference, as the noise is caused by the “hair”, which has a constant shader applied, and not the SEM shader.
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Technical Discussion » Hair-like rendering / noise
- puma.snyder
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Technical Discussion » Hair-like rendering / noise
- puma.snyder
- 121 posts
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I'm rendering some hair-like geometry. They are just 4 point open polygon curves copied to a sphere and they have a width attribute going from 0.006 at the root to 0.001 at the tip. They also have a black to white ramp applied via point attributes which then get referenced by a constant shader. The camera moves slowly.
When I render this setup, I get noise at the tips of each “hair”, which becomes even worse when applying DOF.
I tried rendering with super sample up to 7x7, jitter down to 0 and shading rate up to 2 in various combinations, but the noise is always there.
Here is a short closeup (tga) sequence of the noise with [people.freenet.de] and without [people.freenet.de] DOF.
Any ideas how to get rid of this?
Thanks!
Achim
When I render this setup, I get noise at the tips of each “hair”, which becomes even worse when applying DOF.
I tried rendering with super sample up to 7x7, jitter down to 0 and shading rate up to 2 in various combinations, but the noise is always there.
Here is a short closeup (tga) sequence of the noise with [people.freenet.de] and without [people.freenet.de] DOF.
Any ideas how to get rid of this?
Thanks!
Achim
Technical Discussion » vex port of barnacle shader
- puma.snyder
- 121 posts
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Technical Discussion » Install issue on Mandrake 10.0
- puma.snyder
- 121 posts
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While its correct that you download the license when you first run houdini, you still need the license server. So try installing the lic server, and if afterwards the error is still there, try searching this forum and the one on odforce, I roughly remember reading about this error message.
Achim
Achim
Technical Discussion » sprites, transparency and deep rasters
- puma.snyder
- 121 posts
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Hey Mario, thanks again for taking the time to test it. I rebuild the scene and the shader, and you were right, the standart Pz contains now the correct values, before its was totally messed. ops:
Though this is still a little “rough”, but I guess thats unavoidable when having Z-depth with transparency. But for this case, where the sprites are quite small (and lots of them), it seems I can get away with it
Though this is still a little “rough”, but I guess thats unavoidable when having Z-depth with transparency. But for this case, where the sprites are quite small (and lots of them), it seems I can get away with it
Technical Discussion » Copy SOP
- puma.snyder
- 121 posts
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you could wire all your tile models into a switch sop, and drive the switch parameter via copy/stamping
Have a look here
http://www.sidefx.com/community/interact/mailarchive/index.php?view=WEB&msgid=3CF5584A.28B9E69D@fa.disney.com&perpage=20&revdate=off [sidefx.com]
Cheers
Achim
Have a look here
http://www.sidefx.com/community/interact/mailarchive/index.php?view=WEB&msgid=3CF5584A.28B9E69D@fa.disney.com&perpage=20&revdate=off [sidefx.com]
Cheers
Achim
Technical Discussion » sprites, transparency and deep rasters
- puma.snyder
- 121 posts
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Too bad, this doesn't work either, because
if(myAlpha>0)myPz=Pz; >> this works fine
but
else myPz=1e+6 >> heres the problem
In this case myPz should have the value of Pz of the sprite behind it, and not 1e+6.
So there must be another way, but maybe I'm just heading in the wrong direction for what I am actually after.
In fact I want to create some kind of atmosphere which reacts to an Object passing by (I'll answer in the other thread over at odforce after some sleep). So for now I use a bunch of particles, and thought I could use sprites with a perlin noise pattern for rendering. When trying to add depth of field I ran into this problem. I assume for nearly every way of rendering this, I have to use some kind of heavily transparent objects, so there must be a way to do this :?: , or would you take a completely different approach :?:
Thanks again
Achim
if(myAlpha>0)myPz=Pz; >> this works fine
but
else myPz=1e+6 >> heres the problem
In this case myPz should have the value of Pz of the sprite behind it, and not 1e+6.
So there must be another way, but maybe I'm just heading in the wrong direction for what I am actually after.
In fact I want to create some kind of atmosphere which reacts to an Object passing by (I'll answer in the other thread over at odforce after some sleep). So for now I use a bunch of particles, and thought I could use sprites with a perlin noise pattern for rendering. When trying to add depth of field I ran into this problem. I assume for nearly every way of rendering this, I have to use some kind of heavily transparent objects, so there must be a way to do this :?: , or would you take a completely different approach :?:
Thanks again
Achim
Technical Discussion » sprites, transparency and deep rasters
- puma.snyder
- 121 posts
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Mario Marengo
1. Go back to the shader and export “the right thing”. That is to say: add an export float parameter (let's call it myPz) with a default value of, say, 1e+6.
Then inside the shader, you will assign it the correct (alpha-modulated) depth value (something like if(myAlpha>0)myPz=Pz; else myPz=1e+6;, or maybe a continuous range across the AA region, like myPz=fit(myAlpha,0,1,1e+6,Pz);), then use *that* variable (instead of plain Pz) for your deep raster layer.
Hey Mario, thanks very much, that sounds good. I'll give that a try, but there is one thing I am not sure about,
will the fit() approach result in identical depth values for points (at the same distance) when I comp
this pass and another (background) pass which uses standart depth map calculation?
Mario Marengo
2. If what you're after is nothing more complicated than the global Pz, modulated by “coverage” or “existence”, then there may be a comp solution. Multiply the Pz layer by the alpha channel (which you should convert to a float) of your RGBA image, and then comp the result over a 1-channel float image with a constant high number (sey 1e+6)
Thought about that soluation as well, but it unless I did something wrong, it won't work, because
Lets say there are 2 sprites which overlap, the one in the back is seen through the transparent areas of the one before it,
and when I multiply the Pz plane by the alpha, it has the depth info from the one in front of it, because the depth channel has
the complete sprites in it.
Gonna try option 1 now
Achim
Technical Discussion » sprites, transparency and deep rasters
- puma.snyder
- 121 posts
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Hi all
I'm having having a hard time working with sprites, transparency and deep rasters. The sprites are shaded with some noise, and composite fine with the background. Now I want to render out a Pz plane for adding depth of field in halo. But in the Pz channel I see the complete sprites, and not just the noise, and this of course results in unusable depth of field.
What do I have to do to get this working correct?
Thanks in advance
Achim
I'm having having a hard time working with sprites, transparency and deep rasters. The sprites are shaded with some noise, and composite fine with the background. Now I want to render out a Pz plane for adding depth of field in halo. But in the Pz channel I see the complete sprites, and not just the noise, and this of course results in unusable depth of field.
What do I have to do to get this working correct?
Thanks in advance
Achim
Technical Discussion » GI light black with sphere sky in scene | random numbers
- puma.snyder
- 121 posts
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no idea about question 1, but for the second one, I think you need to feed the rand() function with a different argument for each “copy” in order to get different values from it. If possible, put them all in one object and use copy stamping, then you have access to $PT as an argument for rand().
If this is not an option, you could try using the opdigits expression inside your argument. I never used it, so you need to look it up in the expression pdf.
If this is not an option, you could try using the opdigits expression inside your argument. I never used it, so you need to look it up in the expression pdf.
Technical Discussion » batch render. the easy way.
- puma.snyder
- 121 posts
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just put down as may mantra rops as you need, set each one to a different camera, and in the scipts tab of your mantra rops,
in the post render script parameter, enter “render” and the name of the rop you want to be rendered after the current render job is finished.
in rop: “mantra1” enter “render mantra2” (without the quotes)
in rop: “mantra2” enter “render mantra3”
in rop: “mantra3” enter “render mantra4”
in rop: “mantra4” enter …..
in the post render script parameter, enter “render” and the name of the rop you want to be rendered after the current render job is finished.
in rop: “mantra1” enter “render mantra2” (without the quotes)
in rop: “mantra2” enter “render mantra3”
in rop: “mantra3” enter “render mantra4”
in rop: “mantra4” enter …..
Houdini Lounge » Loading HScritp via object text port?
- puma.snyder
- 121 posts
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as far as I remember, the script creates a dimmer variable which you can adjust in the aliases/variables dialog.
Houdini Lounge » Loading HScritp via object text port?
- puma.snyder
- 121 posts
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did you try it without adding an extension?
If that does not work, try ading .cmd to the file generated by lightgen and then source it via the textport.
If that does not work, try ading .cmd to the file generated by lightgen and then source it via the textport.
Technical Discussion » Randomizing a value
- puma.snyder
- 121 posts
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take a look at the fit function (type “exhelp fit” in the textport)
fit(rand($PT), 0, 1, ch(“../box1/sizey”), ch(“../box2/sizey”))
Hope this helps
Achim
fit(rand($PT), 0, 1, ch(“../box1/sizey”), ch(“../box2/sizey”))
Hope this helps
Achim
Houdini Lounge » Color gradients via Displacement
- puma.snyder
- 121 posts
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Technical Discussion » resampling line
- puma.snyder
- 121 posts
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you could try chf() expression in the point sop
line sop (Direction = 1,0,0)
resample (Lenght = 0.01)
wire this in a point sop and create a spare channel (name it spare1)
In the channel editor set a keyframe for spare1 at frame 0 (value = 0) and a keyframe at frame 100 (value = 1)
in the tx parameter of your point sop, put
chf(“./spare1”, $PT)
now you can control the distribution of points by inserting additional keyframes (between frame 1 and 99) in your sparechannel.
Hope this gets you started
Achim
line sop (Direction = 1,0,0)
resample (Lenght = 0.01)
wire this in a point sop and create a spare channel (name it spare1)
In the channel editor set a keyframe for spare1 at frame 0 (value = 0) and a keyframe at frame 100 (value = 1)
in the tx parameter of your point sop, put
chf(“./spare1”, $PT)
now you can control the distribution of points by inserting additional keyframes (between frame 1 and 99) in your sparechannel.
Hope this gets you started
Achim
Technical Discussion » Copy SOP?
- puma.snyder
- 121 posts
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for a quick test use a
sphere sop (center= 5, 0, 0)
copy sop (rotate= 0, 360/$NCY, 0)
and play with the Nuber of copies
cheers
Achim
sphere sop (center= 5, 0, 0)
copy sop (rotate= 0, 360/$NCY, 0)
and play with the Nuber of copies
cheers
Achim
Houdini Lounge » using created Attributes
- puma.snyder
- 121 posts
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I think you dont have access to $PR in the polyextrude sop, so maybe this works
Put down a box sop
append a polyextrude, set local scale values to 0.999 and toggle create Output groups on
append attribcreate sop and set it to work on extrudeFront group, for the value use something like rand($PR)
and for the primitive attribute name use “extrude”
append a primitive sop, set it to work on extrudeFront group and in the translate params put
$NX*prim(“../attribcreate1”, $PR, “extrude”, 0)
$NY*prim(“../attribcreate1”, $PR, “extrude”, 0)
$NZ*prim(“../attribcreate1”, $PR, “extrude”, 0)
Hope this works
Achim
Put down a box sop
append a polyextrude, set local scale values to 0.999 and toggle create Output groups on
append attribcreate sop and set it to work on extrudeFront group, for the value use something like rand($PR)
and for the primitive attribute name use “extrude”
append a primitive sop, set it to work on extrudeFront group and in the translate params put
$NX*prim(“../attribcreate1”, $PR, “extrude”, 0)
$NY*prim(“../attribcreate1”, $PR, “extrude”, 0)
$NZ*prim(“../attribcreate1”, $PR, “extrude”, 0)
Hope this works
Achim
Technical Discussion » VEX SEM Shader and shadows
- puma.snyder
- 121 posts
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Thank you for the tips Antoine
I think I can figure out how to thin out the shadows depending on how parallel/perpendicular
the shadow casting ray is to the camera, but as I never wrote a shadow shader before, I have
no idea how to darken only some specific parts (only those which get a shadow from another object)
So could you or someone else please tell me how to do this?
By the way, this is the picture I'm trying to recreate.
http://www.sidefx.com/forum/viewtopic.php?t=2385&sid=537fc8410713c637d487762a47f1749a [sidefx.com]
Thanks again
Achim
PS: was the SEM shot you did for a movie? If so please tell me for which one, so I can have a look at it
I think I can figure out how to thin out the shadows depending on how parallel/perpendicular
the shadow casting ray is to the camera, but as I never wrote a shadow shader before, I have
no idea how to darken only some specific parts (only those which get a shadow from another object)
So could you or someone else please tell me how to do this?
By the way, this is the picture I'm trying to recreate.
http://www.sidefx.com/forum/viewtopic.php?t=2385&sid=537fc8410713c637d487762a47f1749a [sidefx.com]
Thanks again
Achim
PS: was the SEM shot you did for a movie? If so please tell me for which one, so I can have a look at it
Technical Discussion » I have a particle question?
- puma.snyder
- 121 posts
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Cylibral
Or How to create lighting fx like in the electrical balls where you put your fingers and the lighting follows your fingers
Hi Cylibral
take a look at the Lightning tutorial in geometry pdf/l-systems. This should get you started.
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