Discussion: Kartapullautin contour question

I'm trying to create some contour maps from MN Lidar data (downloaded in laz format)

I'm using las2las (lastools) to get it to las for use in Kartapullautin
When I run it through Kartapullautin I'm not sure what the contour line elevation is, but it's too dense.
Q1: How can I determine the contour elevation? Does it vary from one las file input to the next or is it all generated in pullata.exe?
Q2 To change contour intervals, do I change the pullauta.ini
coordzfactor=1 to some other number? Is higher number less or more contours?

OR... is there an easy way to change contour intervals once file is in ocad or open orienteering mapper?

I guess your data is in feet (or surveyfeet?). You need to convert it to meters. You can do it with lastools las2las. Or set coordzfactor accordingly.

http://www.cs.unc.edu/~isenburg/lastools/download/...

If you place latools las2txt.exe in same folder as pullauta.exe, you will not need need to convert laz files, just drag-drop your laz file on Pullautin.

I used this (for northern Ohio points). I'm not sure what you would use in MN to replace the "OH_N" parts:

las2las -i *.las -sp83 OH_N -feet -elevation_feet -target_sp83 OH_N -target_meter -target_elevation_meter

This keeps it in the state plane tiles. All the tiles were skewed when I changed the plane to UTM. More here:

http://attackpoint.org/discussionthread.jsp/messag...

What I try to do now is combine all the tiles into one big file, convert that whole file to UTM, clip it to the area of interest (which is now square-edged in the UTM plane), and then re-tile it. That way the KP output tiles look good. I'm not 100% sure, but I think the skewed areas have more discontinous lines than the normal output, which lines up amazingly well when the tiles are nice and square-edged.

It's been so long since I did it, I can't remember the lastools I used, nor can I remember the commands. I recommend taking good notes so you don't have to figure it out twice. (I didn't.)

For small areas, I just use that las2las command above and I don't convert to UTM. It's just easier. For anything bigger than a sprint map, I'd work harder to get it into UTM.

Saw this on World of O's twitter stream:

Nice article on tools for map generation from LIDAR data - including download of the tools. Thanks Terje Mathisen! http://tmsw.no/mapping/basemap_generation.html

Thanks for the suggestions. I've had some luck before through trial and error, but did not write down my notes, so I'm starting over.
I'll read the sources, try the recommendations and see what happens. And I'm going to try to keep better track of what I'm doing!

Also, this document says:

All LiDAR data downloaded from the LiDAR ftp site is referenced to the State Standard projection, UTM Zone 15, NAD83 Datum (horizontal), NAVD88 (vertical).

So---you don't have to worry about a UTM conversion. Just the feet-to-meters issue.

I'm not certain the command I mentioned above is correct for the vertical part (the NAVD88). It doesn't need the OH_S, obviously, but you'll have to figure out from the readme file how to specify the input and output is UTM in the correct zone for your location.

Map Plop!