Image or Light Keystone

Become a member of the CGSociety

Connect, Share, and Learn with our Large Growing CG Art Community. It's Free!

Thread Tools Display Modes
  03 March 2013
Image or Light Keystone


I work as a projection designer for a living, and dabble in many things including Max. I quite frequently use Max to do pre-viz on projects to see how projections may look on a set, but 9/10 times I just render the set then hack it together in Photoshop.

I have been trying to come up with a way to use ability to turn the spotlight into a projector to rough in actual positions/lensing of where the projectors would be in real life and then do renderings with those for more realistic pre-viz. The problem I have encountered though is I can not find a way to either keystone the light its self (spotlight set to rectangle with projector map enabled) or which I think would be the better solution, have the ability to corner pin/keystone the material I am using for the projector map.

Of course I can pre-keystone everything in photoshop/after effects, but at that point im right back to where i started. My goal is to speed up my workflow and actually get a sense of how everything will fit together within max, without having to fake it in PS/AE and hope it all works in the end.

If anyone knows a trick in max that would allow me to do this, or a plugin, or custom shader or what ever it would be greatly appreciated. I am at my wits end searching for the answer.
  04 April 2013
If i understand you right, Camera Mapping with the Vray-Physical-Camera should do it.
You can keystone using the vertical & horizontal shift. See Attachment. In the example i am projecting a texture with horizontal shift at a plane.
Attached Images
File Type: jpg VrayCameraMapping_with_Shift.jpg (76.9 KB, 14 views)
  04 April 2013
The problem with that is its based in the cameras space. My goal is to actually project light, much like a real video/film projector would. So it wouldn't be a camera effect but actual light source like you get using a spotlight with the projector map.
  04 April 2013
actually, using the technique I suggested can project light on a surface and its possible to keystone the image with the vertical and horizontal offset and shift.

this works very simmilar to a spotlight with a projector map.

in this example,the camera projects a keystoned map on a wall. the material of the wall has a "camera map per pixel"-map in the self-illumination slot with a simple 6x9-tiles-map-texture.
the small box in the upper corner (where the camera is) visualizes the projector.

Isn't this what you're after?
Attached Images
File Type: jpg VrayCameraMapping_with_Shift_02.jpg (93.9 KB, 12 views)
  04 April 2013
If that is the case it may work. I misunderstood how the camera mapping worked. Will objects in the path of the camera cast a shadow? Are you able to control the fov of the camera to simulate the lens ratios?
  04 April 2013
i think the objects in the path won´t cast a shadow. at least they did not in my simple test, but there maybe more advanced methods which can do that. my camera projection knowledge is rather limited.
the fov of the camera to simulate the lens ratios works.

i see you would rather use the spotlight with the projector map and there may be a way to keystone the projection with a spotlight. you can use the skew modifier on a spotlight to do a vertical and horizontal shift.
if you want to try it, you may need to use 2 skew modifiers (one for horizontal and one for the vertical adjustment). to get the desired result, the adjustment of the gizmo of the skew-modifier may be important (especially the rotation of the gizmo).
  04 April 2013
Thread automatically closed

This thread has been automatically closed as it remained inactive for 12 months. If you wish to continue the discussion, please create a new thread in the appropriate forum.
CGTalk Policy/Legalities
Note that as CGTalk Members, you agree to the terms and conditions of using this website.
Thread Closed share thread

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

vB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Society of Digital Artists

Powered by vBulletin
Copyright ©2000 - 2006,
Jelsoft Enterprises Ltd.
Minimize Ads
Forum Jump

All times are GMT. The time now is 11:22 PM.

Powered by vBulletin
Copyright ©2000 - 2018, Jelsoft Enterprises Ltd.