Blender object placement on image background

Support Basics & Interface
1

Hi All,

I want to be able to place a Blender object, a simple cube for example, on a background image - a photo of a table top.

The problem is - how do I orientate the cube in Blender so it looks like it’s on top of the table? Similiarly, I would want to model part of the table so I could create shadows for the object.

Any tips?

Cheers,

MadMark

2

Yeah. Here’s how I would do this:

  1. Measure your table.
  2. Build a scale model of the tabletop in Blender.
  3. Place your camera in Blender where you think would be a good approximation of the real camera.
  4. Split off a new 3d window and make it a camera view.
  5. Go into the “buttons” mode for this window, and set it to have a background image, size 1. When you go back to the 3d view, your image should fill the extents of the camera. You may want to set the opacity of the image lighter or darker depending on your monitor, in the button view.
  6. Grab the tabletop in your other 3d view.
  7. Move it around a little, watching how the wireframe lines up with the picture in the camera viewport.
  8. Once you have it positioned properly, make your cube.

Then, you can either use a backbuffer in the render buttons to place your background image in the final render, OR (my preference) you can render without backbuf, but with the Key button down to an rgba targa file, then composite more carefully in your image editor of choice.

3

is it really neccessary to do all of that? I had to do something similar recently and it seemed pretty easy. I did:

set the real image as the world texture
create a plane, and angle it towards the camera so that it looks similar to the table top
just move it around or edit it so that it covers the entire table top-just move, render and move it again till it matches
place your object so that it is where you want it-make sure it is on the plane though
set up your spot to cast a shadow
make the plane shadow only

it turns out pretty good

4

is it really neccessary to do all of that?

You could do worse! D/L Icarus from http://aig.cs.man.ac.uk/icarus/ and use it. It compenstaes for camera lens distortion and view distortions etc, then pulls the textures right from the pic. You can even use a video from a moving car and recreate a building. Eeshlo made an import script for it too, (of course!). Buggy as heck, but kinda fun to a point. It has ‘garbage’ tools too, so you can make like… people on the street disappear.

5

try this: http://www.weirdhat.com/blender/comp-tute/

Martin

6

I could’ve simplified it to: model your tabletop - set the bg pic of the camera view to your image - match positioning. But not knowing anyone’s skill level who might be reading this now (or in the future if they do a search before asking a similar question), I thought I’d give the most detailed step-by-step that I could. I also like to talk a lot. :stuck_out_tongue: