Note : Post moved by myself
@frankiezafe wrote :
Hello guys, ‘hope that the unity vs blender day was great!
to do something in cycle that seems a bit hard: simulation of a video
projector -> it has a cone and an image texture. The worse is that,
even if i place a mask in front of the spot, i still have a circle of
light on the screen… >> http://frankiezafe.org/fileadmin/sites/frankiezafe/labo/innerlandscapes/video-projector.png
An area lamp is not good either because it has no cone.
The best would be to have a kind of “laser” light, meaning ultra-directional particules.
Live & Learn
I’m afraid you’ve made a mistake somewhere as it should work
See here : http://bbug.tuxfamily.org/index.php?p=/discussion/147
Try using volume instead of plane maybe ?
Live & Learn
Cycles doesn’t support volumetric in lamps. As you can see, there is no volume socket in the shader. You need to do that on the world shader or inside an object. A video texture in the front of the lamp with a transparent value should work too.
Waouw! Thank you guys! (i didn’t see that you moved my question to another discussion…)
Anyway, here is the image (in the bottom left, the projected image) – more image here http://lab.frankiezafe.org/index.php?id=117&tx_ttnews%5Btt_news%5D=561
Maybe I’m wrong but when I did the tests, a lamp with a texture doesn’t work very well. Try to change the rotation of the lamp and see how it behaves? I’m not sure it will be accurate. Maybe your setup with point mapping will solve that! it would be awesome, I’ll try it tonight!
Indeed, it doesn’t work well with texture that is directly plugged to the light.
The tutorial you linked in your website is actually wrong because the mapping will depend of the angle of the lamp and as soon as you will leave the default rotation values of the lamp, the projection will be wrong.
The only solution I see is to model the gobo in front of the lamp like I or David did before.
@vincentg >> tuto adapted 🙂 i explain now the relation between object orientation and mapping rotation. The gobo solution is tricky to tune (ratio, throw angle, etc.), that’s why i’m following the texture solution, faster to adapt depending on the video projector i want to simulate.
next phase: i would like to find a relation between my video projector lumens and the strength of the spotlight in blender. Do anybody have an idea on how to calculate this?
No, this is a spotlight too.
What’s wrong with your rotation_euler.x? is there an error message? you can try rotation_euler for x, rotation_euler for y, sometime it helps…
ok, auto-execution of python was disabled 🙂
i use this expression: radians( 360 ) – var, testing the whole process now
really! – test it with a texture image, that may be the problem
question: how do you have a so smooth preview rendering?
Already tested with an image texture and same “issue” (not even sure that’s a issue). My texture is well projected but is tiled, 4 times, 8 times, … depending of the cone size. I suppose this is normal because a lamp has no “frame” or border like the texture. But I don’t really know.
Try with a big spot shape, maybe you will see what I have.
This is the viewport shading in rendering mode (shortcut: shift+z)
How did you remove the tiling and get the perfect framing of the image texture?
I have the same deformation but I suppose it’s because a spot light emits all rays from the same point location in all the directions like a sphere lamp. That should be why the shadow of a spot is not parallel.
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