Hey all. If you’re like me and don’t have enough money for a LIDAR scanner but need to make precision 3D models for projection mapping or content creation, here’s a relatively quick and cost effective method.
All you need is a decent camera and a 3D modeling program like Blender. For this tutorial I am using my cell phone camera and Blender 2.74.
Start out by finding a good angle of the set or object you will be projecting onto. This method is a lot easier if you are working with rectilinear objects. You will want to try to find an angle where you can see as many sides of the object as possible(Top, side, and front are best.) Take a photo of your set so that your camera is as parallel with the ground as possible, this will make it easier to align in the virtual environment. Its generally best if you can be as close to the angle of the projector as possible.
Next take you image into your 3D modeling environment and apply it to show up in the background of your camera. In Blender there is an option to add an image in the bottom of the right side tool bar. I find it easier to set the image to the front option and set the opacity like so.
Add a ground plane/wall/cube to compare the perspective of the image to the one of the camera. I find it works better if I add an empty for the camera to look at, then align elements I know to be square with the virtual elements I placed. In this case I am concerned with how converging line of the corner of the wall line up with the virtual representation. If I can get these to align perfectly, I can reproduce the rest of the image easily. This part take time and patience. I recommend finding the focal length of the camera you are using and setting it to be the same in the virtual camera.
Once the reference elements are in place, its time to start placing the other elements. You should not touch your camera alignment unless something looks very off.
I’ve added a simple cube that is going to become one of the boxes in the image. Tab into edit mode and align the origin of the box to be one of the corners. This will make it easier to align with the image. Place one corner of the box with the matching corner in the image and rotate until edges align. then scale each side appropriately referencing the image.
Once you have everything lined up and looking right, you’re done! You can now start UV mapping and planning out some interesting visuals.
For more information on Camera Mapping, check out this tutorial.
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