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16

Given that you have the LIDAR DEM, you should use the streams derived from it. That guarantees perfect registration. The crux of the idea is to estimate mean slopes in terms of the elevations at the ends of the segments. One of the easiest procedures is to "explode" the stream network into its component unbranched arcs. Convert the collection into a ...


13

Commercial: FME Desktop " ability to take a point cloud that has no color information on it, and overlay it into an orthophoto to produce a colorized point cloud" http://blog.safe.com/2012/01/beating-lidar-into-submission-with-fme-2012/ LP360 Add-on to ArcGIS http://www.qcoherent.com/products/index.html LP360 for ArcGIS™ (Basic, Standard and Advanced) ...


11

Your PointsXYZIC is now a numpy array. Which means you can use numpy indexing to filter the data you're interested in. For example you can use an index of booleans to determine which points to grab. #the values we're classifying against unclassified = 1 ground = 2 #create an array of booleans filter_array = np.any( [ PointsXYZIC[:, 4] == ...


10

ESRI has a pretty good help section on LiDAR (below). For more formal details on LiDAR, I would recommend the following books: Topographic Laser Ranging and Scanning: Principles and Processing Airborne and Terrestrial Laser Scanning Remote Sensing and Image Interpretation LiDAR Laser Returns Laser pulses emitted from a lidar system reflect from ...


9

This sounds like Tom Patterson's work on Resolution Bumping GTOPO 30 in Photoshop. The theory is described well enough to be adaptable to other software, though work needs to be done coming up with the specifics. The basic idea is to generalize (blur) one data set, a lot, to emphasize the general shape and hide specific detail and then blend the hi-res and ...


9

FUSION/LDV is a powerful and solid open source option developed by the USDA Forest Service to analyze and visualize LiDAR data. General information about FUSION can be found here: Overview of FUSION features: Generates DEMs from point data Produces bare earth surfaces from unfiltered points Displays image data for background reference Subsamples large ...


9

ArcGis has a new LiDAR dataset at 10.1 which will allow you to view your LiDAR data directly and also see more information than what's in a raster... for example you can add to ArcMap and then filter down the display to just tree classes, or just first returns! LiDAR data contains much more than just elevation, there's intensity that is stored by default ...


8

Tips: Note: Your computer has plenty of spec: Develop a full or partial disk cache whenever possible. Disk caches allow data to be pre-rendered for optimum ArcGlobe/ArcScene display performance. Store ArcSDE/ArcScene data sets using the Cube projection This will avoid pyramid resampling and data reprojection for ArcGlobe. ...


8

I read about variety of algorithms for the job (ie. as per @Hornbydds link). I tried couple appoches, and the best results in my case yield Standard Terrain Analysis from SAGA. Here is what I did and why: Dikes are usually highest feature in the vicinity of river channel, so I turned them into channels by flipping DEM (MapAlgebra DEM * -1 or for ...


8

A common mistake (that I've made too) is to down-sample a raster using the resample tool with bilinear interpolation. See this answer for an explanation why this is not good. A raster can be down-sampled in three steps. The first step might not be required. Reproject the raster to the target extents. Use bilinear interpolation, and keep the output cell ...


8

laspy is another good LAS read/write software. It supports working with the data directly in numpy arrays and a number of other nice Pythonic features. It isn't processing software per se, however. PDAL has the ability to use Python as an in-pipeline filtering language, but this isn't a processing engine either. There isn't too much in the Python quiver ...


7

Sounds like you're wanting to do this in batch (don't blame you) As STH said, looks like Global Mapper will indeed do batch conversions. Nice price as well. FME Desktop can do using the RasterDEMGenerator transformer and a bit of linking with reader/writer, but you'll need the Pro version, not available in the ArcGIS Data Interop extension. If free is ...


7

The tool lasgrid.exe (README) from LAStools does a "direct" conversion with gridding (without triangulation) very fast. The tool las2dem.exe (README) from LAStools rasters the points via a temporary TIN. Regards, Martin @lastools


7

It all depends on where you draw the line. Regardless, this problem looks like it can be readily addressed using the morphological functions available in Spatial Analyst, especially thresholding (performed with "<" and ">" local operations) and "RegionGroup" to identify and extract components. Although I do not have access to the DEM to illustrate, the ...


7

libLAS can indeed be used commercially. So can Martin Isenburg's LASlib, which is LGPL, and speaking as the author of libLAS, faster and more completely supported than libLAS. Both are indeed C++ libraries, however, and there isn't too much in the ASPRS LAS space for native .NET. I'm also the primary author of PDAL, and PDAL can also read ASPRS LAS data, ...


7

There is no way to get floor heights from a lidar pointcloud. Lidar is captured by bouncing lasers off the groundsurface and measuring the bounced back pulses. Therefore there is no way for the lasers to 'see' through the roof of a building and return a floor height. However, a solution to this may be to classify your las point cloud into ground and non ...


7

Inside a Geodatabase, there are certain ways you can't name a table or Feature Class. Beginning with a number is one of those ways. Validating Table and Field Names in Python: http://resources.arcgis.com/en/help/main/10.1/index.html#//002z00000020000000 Try renaming your table to las_1 or something and see if it works


7

This looks like a valid workflow for this task. However, depending on the level of accuracy that you work with, you will miss out on things like pipes under roads allowing for ditches and small creeks to flow past the road. These would probably require some field work to identify though. You don't mention which software you use, but for ArcMap point (6) ...


7

If you have a raster DEM already, then there is a tool that I developed in Whitebox Geospatial Analysis Tools called Remove Off-Terrain Objects, contained within the LiDAR toolbox, that works well for creating bare-earth DEMs, particularly in urban and agricultural settings. It works less well where either the terrain is steeply sloped or the forest cover is ...


7

You already have a DEM; there is no need for you to create one. The DEM is contained within your files, i.e. you have two copies of the DEM, one contained within an ArcGIS ASCII raster and the other within a GeoTIFF. These are simply file formats that contain the raster data that is your DEM. One of the most common formats for a terrain model is as a regular ...


7

It depends on what version of the LAS specification you are using. If it is 1.3 or less, then the specs define georeferencing information using pre-defined (see specs) variable length records (VLRs) using the same format as the GeoTIFF: Georeferencing for the LAS format will use the same robust mechanism that was developed for the GeoTIFF standard. ...


7

Dark areas = low reflectivity. Light areas = high reflectivity. My guess is the dark squares simply has not reflected light back to the transceiver and then you have no xyz data here. For the floor my guess is that light is deflected away from aperture and not towards aperture, except for the holes. This depends of course of the sensor and the setup. In ...


6

How to compare two Digital Elevation Models (DEMs) Solution using the software R. #------------------------------------------------------------------------- #Creating a reproducible example library(raster) #simulating raster_1 f = system.file("external/test.grd", package="raster") DEM_1 = raster(f) #simulating raster_2 DEM_2 = DEM_1 # ...


6

Try running the sp_help_spatial_geography_index stored procedure to get details on how your spatial index is being used. You should be able to use something like: declare @ms_at geography = 'POINT (-95.66 30.04)' set @ms_at = @ms_at.STBuffer(1000).STAsText() exec sp_help_spatial_geography_index 'lidar', 'SPATIAL_lidar', 0, @ms_at; Post the results in ...


6

There are a number of places where footprints can come in very handy Public Sector: Taxation: As @Mapperz said, taxation is one area. The percentage of property that is built on is sometimes used as a tax criterion. Planning: Knowing where structures already exist on property can help in the planning process due to applied setbacks and minimum ...


6

FullAnalyze is open source waveform software. http://fullanalyze.sourceforge.net/ SPD is a waveform file format with open source processing software. http://www.spdlib.org/doku.php


6

Sub-centimeter elevation? No. This article provides a good overview of LiDAR and the associated errors (Range, Position & Orientation). Operationally, when working with LiDAR data we assume a potential 5-10cm vertical and horizontal error. At times it may be much more accurate, but it's not sub-cm.


6

(The answer is based on my and others' comments above; haven't really tested it) Store the points as MultiPointZM. The best grid size would probably be dependent on access patterns and you need to do some testing on this. A regular grid with a spatial index should make queries quite fast. If 3d access is important then MultiPointZM could be 3D block ...


6

A paid LAStools toolbox has been released for QGIS by Rapidlasso GmbH. Instructions on installing it can be found at: http://rapidlasso.com/2013/09/29/how-to-install-lastools-toolbox-in-qgis/ You can find the pricing information on this page: http://rapidlasso.com/pricing/


6

When converting a LiDAR dataset to a DEM, you are taking a set of discrete data points and converting them into a single, continuous dataset. Let's say that your .las file contains X (latitude), Y (longitude) and Z (elevation) values with an average resolution of ~1 meters. The resolution here is really important- we're only talking about an average and so ...



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