I'm trying to get chalk graphics I've made in Photoshop to integrate realistically/seamlessly with the live video background. So far, I haven't had any luck. My tutor suggested using displacement map but I believe the background is too fine for it to work.
To sell the effect, I think you need to get the uneven look of chalk, Andrew Kramer did a tutorial on creating blueprints that I think might help you. Using some textures and such, will help make it look more organic.
Creating a displacement map from the luminescence of your wall will also sell the effect. It doesn't have to be much, just a slight displacement. Make a duplicate layer of your wall and precomp it and play with the levels/contrast and use that as your displacement map.
The last step would be to experiment with blending modes. Your wall should show through a bit as it the chalk color will change some as it moves over different areas of the wall.
Johnny Cuevas, Editor
"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.