# Sampling geometry for LED Matrix

Hey
I have a volumetric(3d) LED array and I’m trying to figure out the best way to send geometry to it.
I have read this thread viewtopic.php?f=4&t=6075&p=22968&hilit=led+geometry#p22968 but can’t grok a solution for individual pixel control.

The ideal outcome would be to have a low-res pixel 3d sample area that is sent over artnet to the addressd pixels, with any textured geometry falling over the addressed points to be colour sampled and sent out.
The first issue I see is that geometry in touch is hollow, and sampling points within it would yield nothing…this began my thoughts on using the texture3d top etc but this isnt practical.

The other solution would be to carve the geometry in slices to match the resolution of the LEd matrix and sample point/vertex values. This seems pretty crazy especially at high pixel counts. This also would cause problems for low poly/point geometry where there simply won’t be any points within the sample areas. But I guess the divisions parameter of the carve could add these…but how to sample them at the pixel positions in the real world?

Essentially, how can I setup a 3-Dimensional sampling matrix to loop over the geomtry in world space in touch?

You can use the Divisions parameter in the Box SOP to create a 3D grid of points, it will have points throughout and not be “hollow”.

Perhaps that is an easy way to start? There are many ways to sort the points using the Sort SOP which will give you some simple yet interesting ways to start addressing those points in different ways.
boxDivided.tox (598 Bytes)

thanks Ben
what is hollow would be the geometry that would be sampled AT those points,ie. a sphere’s points will only be at the shell of said sphere rather than a volumetric one.
In fact I’m still at a loss as to how to sample colour values at those points anyway, even if the geometry was solid

You can set up multiple render tops, each with a camera that has clipping planes set to isolate each slice. Work at only the res you need for your LEDS and it will be fast.
You will have to come up with different geometry or render methods that works for this though, because polygons are just planes. Look at the various volumetric rendering methods.