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Using GIS (maps) to find Roxx: A Guide
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Don't know if this was mentioned yet but I want to give a shout out to Global Mapper (I like to notify ESRI that I'm going to go use Global Mapper when they ask if I would like to add any details to the crash report sent back to the mothership after ArcMap can't handle it's shit) GM is IMO and experience better suited to process Raster and Lidar data. Lidar is by far the best approach here. Ferreting out the available data is the biggest hurdle. Some Lidar data sources: https://earthexplorer.usgs.gov/, http://www.opentopography.org/index.php, https://coast.noaa.gov/digitalcoast/?redirect=301ocm, as well as checking state, county, and municipal GIS clearinghouses/catalogs. |
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A Landsat 7 image with 7/3/1 band combo pulls out definition of soil/vegetation/rock boundaries pretty well and you can make some decent attributions to rock type with a 7/5 band ratio. |
Michael P wrote: I don't have ArcGIS. I'm an engineer so I work mostly in autocad. I can get by with most python and java though |
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recommend checking out QGis. FOSS alternative to ArcGIS, and is built on python to boot, so you can do a lot of scripting and custom analysis. |
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I found Lidar for Shawnee national forest where JAckson Falls is located and I believe I will do that Statewide lidar is just too big of a file My plan right now is to convert the lidar break the lidar up into several LAS into a slope raster. The problem I have is that the lidar also includes trees and that will throw off any cliffs. I need a way to derive bare earth but i really do not want to download anything else. The lidar files ar pretty big and are rather cumbersome. |
Luke Nitcher wrote: I know you can sort those kinds of points in AutoCAD, in my experience most statewide data nowadays is tagged with reflective values for each point. The machines can tell what is treetop and what is bare earth. Is the file a .las ? |
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Luke, have you used LAS Tools at all? Should be able to classify ground and then strip out the rest. It's possible it was published with the points classified already. |
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Luke, I work with LiDAR for my research. If you can point me to your source and what program you are working with, I can give you exact instructions on extracting and building an elevation model. |
Michael P wrote: The tools you mentioned work ok for building DEMs if you already have a bare-ground dataset. If I'm correct, you were using an OpenTopography dataset. If so, you shouldn't actually need to process them at all. When you download from OpenTopo, you should be able to select pre-processed products including TIN, bare-ground .las or .laz files, and a number of other outputs. These are processed real-time by San Diego Super Computing Center and can save a lot of processing time depending on your system and size of the dataset. Like Andy mentioned, LASTools, a open-sourced toolset, is available for ArcMap and superior to ArcMap's offerings. It has functions for going from multiple return to bare-ground or vegetated models, classifying custom return bins, or building DEMs, etc. Otherwise http://www.opentopography.org/otsoftware has some other solutions. On the other hand, if you are working with somebody else's data set, let me know what you have (raw data, bare-ground, etc) and I can give a better response  It's an open relationship ;) |
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Forgot to mention. CloudCompare is an open-source, robust tool for visualizing any point-cloud dataset including LiDAR. It is a great alternative to many of the professional products which cost $1000+ and is taught to students along with RiSCAN Pro, the software supported by Riegle scanners we used. Also have to rep it here, this is the project I am working on for my Master's degree, http://serc.carleton.edu/getsi/index.html . My section is not yet available, but the High Resolution Topography unit may be of interest to some of you. There is a section on TLS with basic guides on processing data, etc. |
