how to make character leave footprints in the sand

Good evening,
I have a scene where I need to make my character leave footprints in the sand (not in extreme detail, but "stand off" distance. I have seen this done in movies and video games but I am not sure of the best way. I assume shape keys on the set are used for close ups. I think an image can be used for most of my stuff, but do not know how to make them show up after each step. I may wish to do the same with motorcycle tracks.
Any suggestions?
Please let me know.
Thanks,
Scooter

Maybe dynamic paint will do what you are looking for?

billymcguffin wrote:Maybe dynamic paint will do what you are looking for?

I agree with dynamic paint.

Tutorial:

Good afternoon,
I checked into the dynamic paint and it is really neat. I wonder how it was done with images prior to that. I wonder if that is how the tire tracks are made on race car video games? I have one big problem with dynamic paint. I would have to update my version of Blender. I am currently 15 minutes into an hour long movie and am reluctant to update from 2.58. Everything works right now and updates in the past have caused a lot of problems, some of which take a while to discover the hard way.
I am able to do all of the work on any version I choose because I will be rendering the movie myself since one that long is very expensive (I think mine will be about $20,000 per render) and will justify making a 10 to 20 bank render farm. I got that cost from a render farm calculator based on my systems average render time. Anyone have experience with costs?

Do any of you recall experiences with update problems after 2.58 on animated characters? I had a lot of controller influences change and bones flipping over during animation. I may be interested in an update.

Also,
I found a neat tutorial from Philippe Roubal called Tracks Creator which is great for displaced prints.

Let me know what you know.
Thanks,
Scooter