Re-projection / GPC's

I am having some confusion regarding Re-projections. I am a beginner so please go easy. Thanks

  1. Is Re-projection necessary?

  2. How do I ensure I am entering in the correct re-projection data? The specific coordinates to which the project resides is near: 29.7787884375031, -93.9474410188081. Maybe someone can take a look and confirm which EPSG code I should be using for Re-projection. (For our main CRS, the Horizontal projection is: 32615 - WGS 84 / UTM zone 15N)

  3. While on the subject, can anyone help explain re-projecting height? I have read on a few other posts that if a new Horizontal Re-projection is made, then I may not be able to stick with Ellipsoid.

  4. What happens if we do not incorporate GCP’s?

Any help is appreciated. Thank you!

If you are just trying to visualize point clouds and you don’t need to tie them to GCPs for control then I honestly wouldn’t worry about it, and just enjoy your beautiful points in the Rock Cloud. Just understand that any Processing modules that you order from the ROCK Marketplace will be tied to your projections and if you change them afterwards you will then need to reprocess.

If you have a client that needs GCPs and data in a certain projection they will likely tell you exactly what they want.

Often what can cause issues is collecting GCPs in a different projection than what you are re-projecting into…

As projections are such a wide and confusing field it certainly is beneficial to use the same projection for your GCPs as what you want to re-project into otherwise there can be misalignments between your GCPs and the point cloud.

A truly nice feature of the ROCK Cloud is that you can globally correct your point cloud and align it to GCPs as long as you know exactly where they are in your scan. Enter aerial targets as checkpoints.

Ok so yes for the purpose of Classification (ie: taking out trees for demonstrative purposes), we don’t necessarily have to complete a re-projection.

However, once we are generating accurate topo’s, then we will need to (a) incorporate GCP’s and (b) re-projections.

Does this sound correct?

  1. Yes, No need for reprojection to view/edit a point cloud.

  2. To create precise point clouds as a deliverable for your clients you will likely need GCPs and it to be in the client’s desired projection.