OTOY Forums

Hi,
Does anyone know how I can project an image from a light source onto a surface?
I tried placing an RGB image into the emission channel on a diffuse material and applying that to a planar object, but all I get is a bright glow from the plane. If I dial the power way down and up the gamma to make it much dimmer, I still don't see the actual image being projected onto the opposing surface.
Is there a way to do this?

Try this method i described some time ago: http://render.otoy.com/forum/viewtopic. ... ct#p202254

Thank you gueoct!
I have been working with it. So far the projected image is very blurry. I just shrunk the light even more (to .001cm) and that seems to have helped a bit, but it is still a big blur. Perhaps if I wait long enough it will eventually resolve. I took it to 10K samples but it looks like it will need to go to 50K before I can make out details, if at all.

I suppose that the height of the pyramid and its distance from the projection screen are also factors, but am not sure how I would optimize them without a lot of trial and error. . .

I really appreciate the help. I'll keep playing with it but if you happen to have any more suggestions I am all ears

I wonder if anyone has done this in Max. The thread was for Cinema4D and the principles should be the same, but I can't seem to get it to work.
The specular material with the RGB image in the transmission slot appears to block the light from emerging, even if I dial the opacity of the material down to zero.
If I make the light inside really big I can get a blurry image, but only if I put a shiny material on the sides of the pyramid (bouncing around inside instead of coming from one point of light must be making it blurry). If I put a black material on them no light emerges. The specular material is doing a good job of blocking the light!

There must be some setting in the specular material that will work to allow the light through . . .

Hi Buggy I made test and you can see result, I also attached test scene, trick for clear projected image is to have really small light inside piramyd. I also tested if I move piramyd 8m picture will be still clear projected

Thank you so much Mark! Do you have the option of saving back to Max 2011? Unfortunately I am still in the dark ages in terms of versions. If not, perhaps you can list the settings on the specular material with the bitmap in the transmission slot. I think that is where my problem lies, since I have made the light as small as Max will allow (.001cm). Also, regardless of what light I put in there, the light is not emerging through the bottom of the pyramid.

Here is 2011 version. Hope it helps

You are a star Mark! I was able to open the file and see it render.

My Windows 8.1 went haywire today with gibberish appearing instead of English under icons, in file explorer, etc. After hours of mucking I fixed it by deleting the font entry from the registry and the font files in DOS (it wouldn't let me delete them in Windows) and then reinstalling the Windows default fonts. Now, when I run Max all the dialogs are huge. The text is regular size but spread out and I can't shrink the dialogs down to fit in the page. So, until I find a way to fix this I'm not going to be able to see how you made it work. But the main thing is that it does work and you provided a solution -- Thank you!

buggy wrote:......
I have been working with it. So far the projected image is very blurry. I just shrunk the light even more (to .001cm) and that seems to have helped a bit, but it is still a big blur.....

Check the "fake shadows" option on the specular material.
I don´t know, why this is necessary.
Basically this is like a (physically correct) slide projector: a point light source and a slide in front should result in a projected picture on a white surface ;
without fake, right?

Will do!
I'm still working on my PC. After several failed attempts at rolling back Windows updates I ended up having to reinstall Windows. I just migrated it to an SSD and still have a lot to do before I reinstall Max, but I'll get there eventually.
Thank you.