3 replies to this topic

[Rhienne]

I was wondering if someone would be able to provide some assistance. I am reasonably familiar with ArcGIS but have never worked with a LiDAR dataset before. I have recently been sent one and would like to use the elevation data but I am struggling to know what to do with the files. They are raster files, and in ArcCatalog the preview shows images with only 1 or 2 colours. The attribute table only has three rows with values 0, 1, and 2, and a large integer in the un-titled column next to these. When I plot the data in ArcScene and get base heights from the raster I see topography, but when I go to identify a point I don't get anything that looks like an elevation reading. For this data to be useful I need to know what elevations I'm dealing with. Does anyone know how I would find this information?

Thanks.

[AndrewM]

Hi Rhienne, have you had any luck with this yet? It's possible that this is just a units issue. I've received a number of LiDAR datasets where the elevations have been in millimetres above datum, which can obviously be a pretty large value if you're looking at mountainous areas or large buildings. Could the large integer you're seeing be elevation in millimetres? Hard to know without seeing it, but worth a thought!

[chandlersterling]

You may find this tutorial from the GIS Collective helpful. It's about how to process LiDAR imagery with Arc, which seems like that's what you're doing (or trying to do!).

http://giscollective...ta-into-arcgis/

Feel free to stop by the GIS Chat over there with other questions!

Edit: You probably won't want to use the projection used in that example, however, so be careful with that!

Edited by chandlersterling, 29 August 2012 - 03:24 PM.

[tonyw]

Hi Rhienne,
How did you make out with your LiDAR data? My workflow with a LiDAR raster file was to generate contours at intervals I specified which gave me elevations and slope. The raster would be viewed in 3D model over which I could drape the air photos taken by the aircraft at the same time. I'm using Manifold GIS, not sure the corresponding workflow in ArcGIS.

-Tony

I was wondering if someone would be able to provide some assistance. I am reasonably familiar with ArcGIS but have never worked with a LiDAR dataset before. I have recently been sent one and would like to use the elevation data but I am struggling to know what to do with the files. They are raster files, and in ArcCatalog the preview shows images with only 1 or 2 colours. The attribute table only has three rows with values 0, 1, and 2, and a large integer in the un-titled column next to these. When I plot the data in ArcScene and get base heights from the raster I see topography, but when I go to identify a point I don't get anything that looks like an elevation reading. For this data to be useful I need to know what elevations I'm dealing with. Does anyone know how I would find this information?

Thanks.