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Discussion: Doesn't this imply

in: David_Waller; David_Waller > 2015-12-22

Dec 23, 2015 4:30 PM # 
that its not a sprint if it doesn't fit on a sensible sheet of paper at 1:5, or that you have the base map for two sprint maps?
Dec 23, 2015 8:04 PM # 
Yeah, Rob; I'm sure you're right. I don't know the area well -- I just asked Joseph to outline what he wanted mapped on a google image. I think that he erred on the side of mapping too much. A lot of the area looks residential and/or commercial, so I suspect that there will be large tracts that are out of bounds. I'll have to get with Joseph more closely when it comes time to field check, so that we don't waste time mapping a bunch of crap that we couldn't possibly use.
Dec 24, 2015 4:12 AM # 
If you need lidar processed, let me know. I haven't done any NC lidar in a while.
Dec 24, 2015 2:12 PM # 
I never hurts to have an area that you can map on portion and then use a bit of it with a neighboring portion at another meet. For the LIDAR it probably isn't possible to eliminate the residential/commercial areas without making an excessively large number of tiles. Matthew's skills no-doubt exceed mine but I can provide you a 2nd choice for LIDAR processing.
Dec 24, 2015 4:54 PM # 
Rob, the problem with NC lidar, if I remember correctly, is that it's unclassified. I have notes from last time I did it if you need to do some. I should probably make more effort to classify even our local lidar. Eddie was unsatisfied with the classification of some Kentucky lidar from several years ago, and he was able to reclassify and pull out more detail.

When you look at images made from old NC lidar (with like 4m post spacing) compared to Ohio, Indiana, and Kentucky (which were taken in about that order, with apparently smaller post spacings), the newer lidar tends to have smaller post spacing which creates much sharper images. Also, Kentucky lidar seems to have drastically different post sizes in different areas. I'm guessing there were federal dollars helping along the rivers, to help map flood plains, because that lidar seems to have smaller post size. One place, Kentucky Bend, had files so large I threw away 90% of the points to get tiles I could process. (I actually want to go back and tile it into tiny tiles and see if I can find anything interesting.)
Dec 24, 2015 8:14 PM # 
Thanks guys! I'm not doing lidar on this one, though. As Matthew points out, the quality is only okay, and the resultant contours are so jittery that it's a real PITA to smooth them out in OCAD. More importantly, this is a relatively urban/built-up area. Lots of landmarks, buildings, and vegetation changes, so the contours probably won't be used that much for navigation (and lidar contours of urban areas can be a mess, anyway). I got decent enough contours, already in .shp format from NCDOT, and I'm quite confident that they'll be fine.

Pending negotiations with another park, Josef, our club mapper, will likely be mapping another woodsy park in NC (Alamance Co.). If that goes through, I may ping you guys early next year for some help with lidar-based contours.
Dec 24, 2015 10:22 PM # 
For the future, Aidan and I found a good happy medium for quashing the jitters for our last map. I suspect that it might be somewhat data-set dependent but we did not hand-smooth. I will run some more urban ones and a forest site over the next month and I can pass on if they go ok.

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