Oregon Film Museum: Green Screen Upgrade Project Page Created by Ray C. Freeman III for Interplay, Inc. This page reports on the issues, progress, and status of the the green screen upgrade project

RAW VIDEO The raw video was shot at 1920x1080, as compared to our target resolution of 640x360. For best performance, it will best to down-sample this video to the target resolution. However, before we do that, there are other consideration. One of the advantages of the high resolution source is that we can also pan and crop the video if we want to, to make it work better for our application.

HORIZON LINE Every good photography class teaches the rule of thirds, which is a compositional technique used to create more dynamic compositions. This is a sample image from a website on photo composition. Note that the horizon in this photograph is one third of the way down from the top.

HORIZON LINE Here is a another example from a different website about composition for photographers. This time we see that the horizon line is one third of the way from the bottom. The effect is a dynamic photograph.

HORIZON LINE Here is our scaled video with the one third grid overlaid, and we see that your photographer was paying attention in photography class. Not just this frame, but this entire video, and not just this video, but all five of them are composed in this way.

EYE LEVEL Eye level is very much related to the horizon line. In any image shot horizontally, eye level and the horizon line will match up, as in this photo. In this case, they line up about a third of the way down from the top, and the photo is, indeed, more interesting because of that.

EYE LEVEL These two images illustrate the confusion that can occur when eye level and the horizon line don't line up. Scale miscues and spatial confusion can be unintentionally introduced.

CAMERA EYE LEVEL So where is our eye level? These three random samples indicate that it varies. Sometimes it's less than half way from the top, some times it's more. Almost never is it as close to the top as one third.

CAMERA EYE LEVEL This image shows where the thirds and half way points in the image are. Clearly, eye level is closer to the half-way point line than the one-third line. I will use this clip to explore the idea of moving the horizon to the half-way point instead of the third point baked into the raw video. Fortunately, we can do this because we have plenty of resolution to work with.

SCALED COMPOSITE Here is an image of the raw footage composited into the third of our sample images. Note the high horizon line, and how the two wome n in the car look smaller, because this view would only be achieved if the camera was mounted well above their eye level.

SCALED, PANNED, AND CROPPED VIDEO Here is a frame of our video which has been re-sampled after panning and zooming to get the horizon line into the center of the image. Notice that the eyes of the driver of the car behind us are also at the horizon line, as they should be.

SCALED AND PANNED COMPOSITE Here is an image of a scaled version of the scaled and panned video composited with the sample image. The view is much more natural, and the women have return to their normal size, Note also that the eye level of the car behind is approximately the same as theirs. Since they are all seated, presumably with their seats adjusted properly, so everyone's eyes should more or less line up.

BACKCHECKING OTHER SAMPLE VIDEOS The center is a bit low for this image, but it's acceptable. The camera seems to have been moved lower than usual, as the woman's check is at the center of the picture, not her eyes. However, we don't have the luxury of created a separate background video for every camera angle. We need to find one that works most of the time.

BACKCHECKING OTHER SAMLE VIDEO The camera has been swung pretty low for this shot, so there's a lot of sky. Give that these are three small kids in the picture, it probably makes perfect sense.

CONCLUSION In my opinion, the videos should be rescaled with the horizon shifted to the center line of the image. In some cases, we might want to shift the frame right or left as well, especially when there is traffic behind us, to make the location of that traffic more correct. Notice that I did that in the final three images of this discussion, and both our position on the road and the location of the car behind us looks more realistic. I have the capability to do this scaling, panning, and cropping. Click here for a scaled-only version of bay bridge 2. Click here for a scaled and panned version of bay bridge 2, as proposed. Black borders to left and right are a production artifiact that we can get rid of. I will update when I have done so.