If you have trapcode Particular you could create put your photos in a precomp, use them as a custom sprite and set up a grid emitter.
If not you could set up an expression to space your layers. I would make all layers the same size to start, then you could apply an expression like this the position of the layers. It will automatically space each layer an equal distance from the next layer.(Compliments of Marcus Geduld):
var columns = 10;
var spaceBetweenLayers = thisLayer.width + 10;
var x = ((index-1) % columns) * spaceBetweenLayers;
var y = Math.floor((index-1) / columns) * spaceBetweenLayers;
var origin = [40,50];
origin + [x,y]
Johnny Cuevas, Editor
Thinkck.com
“I have not failed 700 times. I have succeeded in proving that those 700 ways will not work. When I have eliminated the ways that will not work, I will find the way that will work.”
—THOMAS EDISON on inventing the light bulb.