TIL*: How to use Blender to render "millions" of objects like in this render I did of piles and piles of bricks:
This was just a test of the method, and could use some refinement particularly in the background and brick texturing.
The basic method is this:
Create a large number of "bricks"(500+) This can be done by duplicating a brick**, then selecting both, duplicating them... Making an array of bricks in a layer. Make duplicates of the layers stacked on top of each other with space between each layer, with a bit of random rotation and placement. Create a large plane some distance under them.
Run the physics engine, allowing the bricks to fall onto the plane creating a pile of bricks.
Put your camera directly above the pile, looking straight down and give it a square aspect ratio, making sure that only bricks are in the frame.
Render the scene and save the image.
Now you are going render the same scene, but time using something called the "mist pass". The upshot is that this produces a grayscale image that is a relief map of the bricks. Save this image.
Now you need to take both images an do some editing. Each of these imaged are going to be used in a "tiled" material (basically repeating the same image over and over). The problem with the images as they are is that you will see very distinct seams where tiles meet. Thus you need to make them "seamless". Without going into details, this means making where the tiles meet "flow" into each other. How you do this depends on what type of image editor you have.
Now, you start a new scene, create a new plane and scale it up. You create a tiled texture (with this image I went 10 x10) using your first image of bricks, which "paints" a ten by ten grid of images on your plane.
You then take the mist pass image, tile it to the same scale and use it to perform a displacement on the plane (again there are some additional steps needed to make this work that I am skipping here).
This gives you a plane with not only the image of the bricks on it, but also the bumpiness effect of the bricks being real objects.
You now add another larger scale displacement to the plane to create the "hills"
One last step:
At this point, things look okay as long as you don't get too close to the plane. If you do, it becomes quite obvious that something isn't quite kosher.
So here's how to fix that: make a new somewhat smaller plane a put it in the foreground of your scene. Sculpt it into a hill shape. Do like we did before, make a bunch of bricks and let them fall onto the 'hill". This produces a "pile" of brick objects in the foreground and helps to complete the effect.
*I actually did this yesterday, but didn't finish until quite late.
** Both the brick and the later plane have to be assigned as being "rigid bodies" in order for the the bricks to fall and interact with the plane.
