These shots feature the amazing Fleischer Stereoptical Camera , with 3D backgrounds.
Here's another one from "Betty Boop and Grampy" -
http://blog.modernmechanix.com/real-scenery-for-popeye/
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This blog used to have many of the walks posted as Quicktime .mov files which could be downloaded or used to step through the animation frame by frame . Sadly , Quicktime is now pretty much obsolete in terms of the Quicktime web browser plug-in. The Quicktime .mov files I had on the blog won't even play in most browsers anymore.