How do I thin X,Y,Z data?

DennisW

Hello, New member here.

I am a semi-retired civil engineer. I use Global Mapper a good bit, but only the change the projections for data. I do not have much skill with GIS and at this point in my life, I probably won't develop it. I have a fairly simple (I hope) issue.

I have a some channel hydro survey data for the Sabine River. It is in State Plane Coordinates feet. Depths are in feet. I will attached a jpg. The data, going from left bank to right bank is about every 6 inches. For my purposes, 50 ft would be a fairly dense spacing. I need to thin the data, either on input or output. If I could just use every 100th point, that would probably be fine. Ideally, I'd like to enter a minimum distance between points.

This is what the data looks like in case you need to know.

3548114.43, 13950353.71, -42.99

3555100.22, 13948973.42, -42.26

3555100.00, 13948973.02, -42.21

3555099.34, 13948971.78, -42.23

3555099.13, 13948971.38, -42.23

3555098.92, 13948970.96, -42.17

I've used dense data before and read it in as an Elevation Grid and use that to thin the data. That worked well. However, the data cross-sections had you head up or down river are fairly far apart. That is fine, but not good for mapping onto an Elevation Grid.

I appreciate any help someone can give me. I really miss the days when you got a users manual when you forked over the bucks for software.

Thanks

hydro survey 2026.jpg

BenF

Import the data, then grid the data (terrain analysis- create elevation grid) once its done that, right click the new layer and select - layer -export - xyz grid - and select the spacing you desire.

DennisW

hydro survey 2026 2.jpg

Thanks for your response. I've tried gridding it but I had problems.

The problem I have when I grid it is that it puts data between the actual survey cross sections. I want points only along the cross sections, just not so dense.

I hope I have made my issue clear.

Thanks again.