Does PS go directly from a local coordinate system to a geographic coordinate system with the Helmert transformation, or is there an intermediate step?
I've been thinking a bit about my GCP distribution, and transformations to account for earth's curvature. I think that as long as I have good GCP distribution, I'm probably ok, but in situations where I don't have good ground control in the middle of the project, it seems like I can pretty rapidly introduce significant error due to the curvature of the earth.
Another SfM package I've been playing with (VisualSFM) is dealing with this by using an Earth-centered, Earth-fixed coordinate system as an intermediate step, but it does this on camera coordinates, which I don't have. But I started thinking about this a lot more when I read
this post from the Ecosynth blog.
Is this a potential issue with PS, or is earth's curvature accounted for in the transformation? Each of my study reaches are about 5km long, so I could potentially be introducing significant error just in coordinate transformation if I don't have dense enough control (if I understand the math correctly).
Andy
Topic: Earth's curvature, and transforming from local to geographic coordinates (Read 3747 times)
