Background Images and World Problems

I am having some problems with my latest project. In the first scene, I want to have a “tentacle of water” come out of real water, so I motion tracked the footage and I set up a tracking scene. Before even animating or doing the water simulation I tried placing a UV Sphere on top of my footage, switched to Cycles and made it glass, and I was immediately disappointed. Instead of the glass distorting the image behind it, the glass was grey. I am new to blender, and I know that I have to do something with the world tab or something with the background image to fix this. The reason I think it does this is because the world is set to grey automatically, so the glass reflected nothing. I think that because my scene is tracked, if my glass ball were to simply distort the background image and receive the color of the background image behind it it should work properly.

Does anyone have any ideas of how to do this? Some of my ideas included:

  • Playing around with the compositor to get my glass to interact with the background image (Keeping in mind I do not fully understand what Blender set up when I set up the tracking scene)
  • Playing around with the world tab. Maybe I can set the world to be grey, except the video in the background kind of follows and fits into my camera but not in a sphere around my scene

Thank you so much if you can help me. If you need download the .blend file to see my problem, I think it is possible to add any video in the background in the compositor and my video is not needed as long as my problem is fixed.

I know there is a way to do this in blender internal render but I want to do it in cycles so it looks better. Is there a way to duplicate this process in cycles?

Sincerely, Wyvernul


Scene01.blend (821 KB)

I have found a solution but no do not know how to use it. The effect I wanted to get works when I have my world as an Image Texture and that image as a movie, and set the mapping to window. But, that only works in a new .blend because the massive node network set up by Blender somehow interferes and doesn’t let it work. Is there a way I could use the set up tracking scene with the world in the way I stated before so that together my objects could distort the image behind them and make shadows? I just need to find a way to make the world work with a movie as a background image with a mapping of window while the compositor allows shadows ro be created, and I have no idea what to do now.

Sincerely, Wyvernul

Problem solved!

I am new to blender, but I think this might interest you if you want to motion track and use Cycles to render your works. After doing Andrew Price’s tutorial on motion tracking, I switched to Cycles and immediately started playing around with the settings. But what I wanted to do was place a glass sphere on my desk and watch it refract, distort, and make shadows. But, when I placed the sphere it was grey, but made a good shadow. So, if you want to have your object make shadows as well as interact and distort the image behind it, I would do these three things:

  1. Set up your tracking scene
  2. Make sure your clip is set as the background image
  3. Instead of using a clip as an Image Texture for the world, use an image sequence of that clip and set the mapping to window

This should be good, and I suggest just trying it if you want to motion track and use Cycles to put a glass object in your scene