Tagged Questions

LIDAR (Light Detection and Ranging or Laser Imaging, Detection and Ranging) is an active optical remote sensing technology that measures properties of scattered light to find range and/or other information of a distant target.

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2
votes
1answer
35 views

Setting Point Cloud Data Colour from Raster

I was reading this article: http://blog.safe.com/2013/10/14-ways-to-take-charge-of-lidar-data/ Number 12 states that you can change the colour of your point-cloud data by using a raster image. Does ...
2
votes
1answer
53 views

Correcting Classification for LIDAR - ArcGIS

Is there any procedure to automatically correct lidar classification? My LAS Dataset has water listed as ground and buildings listed as vegetation etc... Just wondering if there is any option to fix ...
0
votes
0answers
58 views

How to build a LAS dataset for simple viewing in Arcgis

I've been given a few LIDAR files to show my boss how useful the data can be. The problem I have is that I simply need to be able to view it using LASTools but I need to build a LAS Dataset first. I ...
1
vote
1answer
48 views

Make a Ground Mask raster with the Greater Than tool (DEMs are generated from LiDAR)

I'm trying to see if I can replicate the Esri solar suitability site example from this article. I fail on the creation of the binary ground raster. I have made a Bare Earth raster from LiDAR ground ...
4
votes
1answer
116 views

How to automatically check for lidar flight line overlaps?

I have a series of lidar-based raster products created via FUSION. Since I am working with low density lidar data, many of the raster images show significant striping where lidar returns overlap on ...
0
votes
1answer
109 views

How to remove pixel values below 0 in Digital Elevation Model in ArcGIS?

I made a DEM layer from LAS file (LiDAR).Now for showing a map I have a map like the image below! I wonder how can I remove black area? They have the value -2 to 16! How is possible to set the value ...
13
votes
3answers
254 views

Account for bridge overpasses in a ground DEM to allow for water flow under the overpass

I have a bare earth DEM made from lidar data (A). It works well and has passed all accuracy tests. It is used in storm surge models. The problem we are having is on underpasses. I need to allow water ...
1
vote
0answers
90 views

LIDAR Dataset displaying 500,000 meters to the East of correct position

First post on here.. I've been hung up for a couple days. Why does my LIDAR dataset show up ~500,000meters to the east of the correct position even though a spatial reference/coordinate system is ...
3
votes
1answer
91 views

Elevation maps from point clouds: TPS vs. what other methods

In the reply to another question, @thehealingprocess refers to "...a comparison of interpolation methods for interpolating elevation maps from LiDAR clouds, and in almost all scenarios thin ...
1
vote
0answers
47 views

How to increase FUSION-LTK lidar processing productivity?

I am processing Lidar data with FUSION-LTK. My study area contains 5 blocks of 1000 las tiles per block. Each block is broken into approximately 4 subblocks of 250 las tiles. I am calculating grid ...
2
votes
1answer
361 views

Installing LASTools to QGIS on a Mac (or other LAS processing plugins)

I recently saw this link how to install LAStools toolbox to QGIS. The problem is that the instructions are only for Windows users. Now I wonder if it's possible to install LAStools on a Mac with QGIS ...
3
votes
3answers
134 views

Removing duplicates from large LAS files

Are there any publicly and free (not necessarily open-source) applications that can remove duplicate points from LiDAR clouds? I would like something on the lines of lasduplicate -unique_xyz, which ...
2
votes
0answers
93 views

What can I do with lidar returns of 6 or greater in LAS 1.2 specification?

I have lidar LAS data that contains a number of points that represent returns 6 or 7. The data is supposed to be in ASPRS LAS 1.2 specification, which does not allow return numbers (echos) greater ...
3
votes
2answers
574 views

Creating DSM and DTM from a LAS using a freeware solution

Is it possible to export a surface and terrain model files from an aerial, LiDAR point cloud (LAS) set? I am using SAGA GIS for very basic operations, but I couldn't find this option (and I have a ...
7
votes
1answer
850 views

What Lidar processing tools are available in Python?

I have been using FUSION and the command line FUSION Lidar Toolkit (LTK) to process Lidar data. A broad Google search ("Lidar Python") yielded libLAS and pyLAS as Python lidar libraries, however, ...
2
votes
2answers
88 views

How to handle multiple space separator in Grass?

I try to load a Lidar point cloud in .xyz format to Grass (in QGIS 2.0.1). I tried to input the following options to the 'separator' field: tab, 'tab', '\t'. Just for the unlikely case that it ...
0
votes
0answers
34 views

How to best alter surface from LIDAR for designing low water crossing and its approaches?

I was wondering if you might be willing to help me work out the best way to use LiDAR data for my thesis project. It involves altering the terrain to add low water crossings at various angles and ...
7
votes
4answers
887 views

How to clip LAS data using shapefile polygons and open source software?

I am trying to clip or filter lidar files (las, xyz) using a shapefile that contains multiple polygons. Is there open source software that can do this spatial operation? My las files are enormous, ...
1
vote
1answer
129 views

What is the definition of pt_spacing on Point File Information tool?

I can't find any definition for the outputs of Point File Information tool (3D analyst), specifically the pt_spacing field. Is this the average distance between points, or the average number of ...
2
votes
0answers
70 views

Finding obstructions along a stream with LIDAR

I'm trying to find obstructions to boat traffic (downed trees, collapsed bridges, etc) along medium sized streams (5-15m across). The obstructions may or may not obstruct water flow. I have good ...
2
votes
1answer
138 views

Analyse slope gradient from LiDAR .asc data

I'm new to using QGIS. I have purchased some LiDAR data which downloads as .asc format, is there a way to analyse the terrain slope angle from this data or does it need to be converted into DEM? ...
1
vote
1answer
96 views

What tools or opensource library could I use to deal with LIDAR data(mobile laser scan data)? [duplicate]

I would like to do some reasearch job relating to automatic objects extraction along the road, like road markings, pole-like objects. I have to pre-process the original data before applying my own ...
2
votes
0answers
85 views

Making a simple 3D map for browsers with my current geodata

I want to try to make a 3D map for a small area (10 square miles) with some housing, some roads and some vegetation on it. My geodata is as follows: Shapes with houses/roads/vegetation. LIDAR ...
2
votes
1answer
77 views

Las 1.2 format displays extremely long thin line of points

I am having difficulty properly visualizing aerial LIDAR data from the following source: http://csc.noaa.gov/htdata/lidar1_z/geoid12a/data/1124/ Taking any of the laz files, the point cloud displays ...
4
votes
1answer
116 views

Work flow for Lidar and OCAD

I am updating our maps for an orienteering club in Ilinois. I was very excited to find out that we have access to .las lidar data in 2000x2000ft files. I checked out OCAD11 and it can handle .las ...
1
vote
1answer
103 views

Clip raster with shapefile

I want to clipping raster (Lidar) with shapefile in qgis ver.2.0.1. Which plugin in qgis could I use it ? Thanks for help me.
5
votes
2answers
205 views

How do I get the projection of an LAS file using liblas?

I am using the python api of liblas to read/write las files. I would like to get the spatial reference information of the las file using liblas, but have been unable to figure it out. Can anyone ...
0
votes
1answer
207 views

How do I read SBET file in python?

I have an SBET (Smoothed Best Estimate of Trajectory) file that I would like to read in python. I found these links that discuss options for reading/writing SBET files, but I was wondering if our ...
0
votes
1answer
139 views

Where to obtain LiDAR Data for Romania?

I need LIDAR Data for realizing a urban hydrology study (Romania areas), whence I can get this data? There is a chance to obtain data for this area (Cluj-Napoca city)? I'm PhD student are chances to ...
21
votes
2answers
2k views

Proper workflow for LAS to DEM conversion

I regularly come across LiDAR (.LAS) files with elevation data. When I do, I always struggle to find a way of converting them to a DEM for hydrological analysis. I have developed several workflows, ...
4
votes
1answer
525 views

How to create contours from smoothed DEM instead of using Terrain to Raster?

I'm fairly new to working with lidar and have been assigned the task of creating 2ft contours for the entire county using USGS-provided lidar tiles. Is there a significant difference in the accuracy ...
5
votes
2answers
285 views

How to de-noise a DSM

I have created a DEM, DSM, and nDSM from a LiDAR Point Cloud using SAGA-GIS. I extracted the appropriate returns from the point cloud, then converted to grid, and then closed gaps to fill in any ...
2
votes
1answer
91 views

How to determine line numbers within an LAS file?

I am working with mulipulse lidar data that collects points along a number of lines within the flight path. From what it appears there are four scan lines within the data, at different intervals but ...
4
votes
1answer
107 views

How to add points to LAS copy using liblas?

I am trying to make a copy of a LAS file while inserting new points using python liblas module. The code below creates the copy and adds the points, but for some reason the added points are not in ...
8
votes
4answers
1k views

How to view LiDAR data from a web browser?

I am looking to host lidar data on my own server and give clients the ability to view that data through a web browser as a 3D point cloud (file would be in .las format or equivalent), possibly with ...
3
votes
0answers
91 views

How can I convert LIDAR based measurement to UTM coordinate?

I have lidar based measurement with azimuth elevation and range, I would like to convert this data to UTM coordinate. I know the position of the lidar in UTM coordinate system, so I developed the ...
4
votes
1answer
101 views

How do I use a DHM in tiff format for distance and slope measurements?

I am a student and I have to work out a project about soil loss on a plot. I need basic measurements of this plot such as length, width, area and slope for my erosion calculations. I have got my ...
1
vote
0answers
33 views

LiDAR Basics - How classes are determined at LiDAR data? [duplicate]

LiDAR data have classes as Medium vegetation, Buildings, Ground, Model Key and more. What determines these classes ? is it combination of intensity and scan angle rank ? how to reclassify these ...
1
vote
1answer
114 views

How to add LiDAR Intensity attribute to a point feature class?

I need to convert LASD (ESRI LAS Dataset) to ASCII text file. I've export the data to point feature class (LAS to Multipoint), converted multipart to single part and calculate X Y and Z.My first ...
3
votes
2answers
206 views

How to connect contour lines from two different sources?

How to connect contour lines from two different sources (LiDAR & Photogarametry) in order to obtain continuous and uniform contour lines layer ? how can i interpolate them together ? How can i ...
11
votes
3answers
386 views

How to convert LAS file to numpy array?

I have begun learning how to manipulate LAS data in python and wanted to see how others handle LAS files. I would like to read the points (I am using a numpy array), and filter out classes 1 and 2 ...
2
votes
1answer
227 views

Load LAS files in MapInfo

Is it possible to open LAS files within MapInfo? If so, how is accomplished in MapInfo 10.0?
7
votes
1answer
299 views

Looking for free / opensource Lidar web viewer

I have lidar data which I want deploy my users using web viewer. I will probably hold the data in PostGIS (not sure yet). Is there good opensource/free lidar viewer that I can integrate with ...
1
vote
1answer
149 views

How to compare accuracy of two DEM using GRASS

How do I compare accuracy of two DEM data (lidar and srtm) (possibly through rmse) using GRASS GIS? thanks
0
votes
1answer
476 views

GDAL RasterIO grabbing memory

I have written an application in c++ to read LiDAR files and convert to various rasters using GDAL; this worked very well on small scale tests (47 LAS files) however, when used on a live task the ...
5
votes
1answer
155 views

LiDAR Feature extraction specifications/standards

I have vector data representing forests/trees/buildings that have been automatically extracted from LiDAR data. I am looking for specification/guidance for LiDAR derived products, or any standard for ...
0
votes
1answer
484 views

Is it possible to load an .las file directly into QGIS? [duplicate]

Is it possible to load an .las file directly into QGIS? I would like to be able to load LiDAR data and to be able to do analysis based various feature attributes; e.g., elevation, classifications, ...
4
votes
1answer
1k views

What is the procedure to load LAS files in QGIS 2.0.1?

What is the present procedure to load LAS files in QGIS 2.0.1? After some searching I found a paper outlining the procedure; however, it was for 1.8.something, and related posts here are all rather ...
1
vote
2answers
337 views

How do you convert a .lasd (Lidar) coordinate system?

How do you change a coordinate system for a .lasd (Lidar) dataset? The file is currently in UTM_Zone _15N and I am trying to convert it to IL_East.
7
votes
2answers
297 views

Practical Building Extraction Algorithm Implementation

I've been reading many papers over 3D building extraction using LiDAR data and Aerial images. I see that there are many different algorithms for doing such things, such as this and this. Those ...