[pdal] [EXTERNAL] Re: PDAL and OpenLayers

Thu Dec 26 04:47:33 PST 2013

Roger and Eran,

To create a DEM from Pointcloud data using PDAL, you can use the Points2Grid driver. Here’s an example pipeline. You might also want add a filter to select just the last return or the Bare Earth classification if your data is classified.

For pdal, first create an ascii grid file from (las/pgpointcloud/whatever) using pdal. Then convert to tif via gdal_translate. Then use gdaldem to create the hillshade and color-relief images.

pdal pipeline point2gridpipe.xml
gdal_translate -a_srs epsg:3857 points2grid.asc points2grid.tif
gdaldem hillshade points2grid.tif points2grid_hs.tif -z 5 -az 90
gdaldem color-relief points2grid.tif colorramp.txt points2grid_cr.tif -co compress=jpeg -co PHOTOMETRIC=YCBCR -co tiled=yes

Example pipeline:

<?xml version="1.0"?>
<Pipeline version="1.0">
  <Writer type="drivers.p2g.writer">
    <Option name="filename”>points2grid</Option>
    <Option name="grid_dist_x">1</Option>
    <Option name="grid_dist_y">1</Option>
    <Option name="output_type">idw</Option>
    <Option name="output_format">asc</Option>
    <Filter type="filters.selector">
      <Option name="ignore_default">true</Option>
      <Option name="keep">
        <Options>
          <Option name="dimension">X</Option>
          <Option name="dimension">Y</Option>
          <Option name="dimension">Z</Option>
        </Options>
      </Option>
      <Filter type="filters.inplacereprojection">
        <Option name="out_srs">EPSG:3857</Option>
        <Option name="scale_x">1e-05</Option>
        <Option name="scale_z">1e-05</Option>
        <Option name="scale_y">1e-05</Option>
        <Reader type="drivers.las.reader">
          <Option name="spatialreference">epsg:26911+4326</Option>
          <Option name="filename">pointcloudfile.laz</Option>
        </Reader>
      </Filter>
    </Filter>
  </Writer>
</Pipeline>

--
Michael Smith
US Army Corps
Remote Sensing GIS/Center

From: Roger Bedell <rbedell at coordinatesolutions.com<mailto:rbedell at coordinatesolutions.com>>
Date: Thursday, December 26, 2013 at 5:15 AM
To: Eran Nevo <eran at utilis.co.il<mailto:eran at utilis.co.il>>
Cc: "pdal at lists.osgeo.org<mailto:pdal at lists.osgeo.org>" <pdal at lists.osgeo.org<mailto:pdal at lists.osgeo.org>>
Subject: [EXTERNAL] Re: [pdal] PDAL and OpenLayers
Resent-From: Michael Smith <michael.smith at usace.army.mil<mailto:michael.smith at usace.army.mil>>

Hello Eran,
Another possibility is to create DEM files from the LIDAR data, then use GDALDEM to create hillshaded tiles. I'm not exactly clear how to create the DEM files however...

One you have DEM files, I wrote a tool that can create a seamless hillshaded layer for GeoServer, then it is served up to OpenLayers the usual way via GeoServer.

http://rasternormalizer.codeplex.com/

Here is the result:

http://204.62.18.181/OGI/search.aspx?mapcenterlon=-97.670532226558&mapcenterlat=34.802782432797&mapscale=11&Layers=58d1fa5c-6eb4-4b95-9f42-69cd7277e15d%2C4b945341-bc66-4c09-9df4-26fbb58e4a5b%2C&maptype=OLMap

Roger

On Wed, Nov 13, 2013 at 5:20 AM, Eran Nevo <eran at utilis.co.il<mailto:eran at utilis.co.il>> wrote:
Yes , it must be run through browser

On 13 בנוב 2013, at 03:10, Chris Foster <chris.foster at roames.com.au<mailto:chris.foster at roames.com.au>> wrote:

Does it need to run in a browser?  If not, I've been working on a
desktop-based lidar point cloud viewer which might help you out - see
http://c42f.github.io/displaz.  I'm close to a 0.2 release which will
include a binary installer for windows.

Cheers,
~Chris

On 13 November 2013 01:26, Eran Nevo <eran at utilis.co.il<mailto:eran at utilis.co.il>> wrote:
I'm looking for some kind of lidar viewer

On 12 בנוב 2013, at 17:15, "Michael P. Gerlek" <mpg at flaxen.com<mailto:mpg at flaxen.com>> wrote:

Eran-

The sheer volume of point cloud data, as Howard says, makes it very hard to
display in a traditional web browser system, e.g. OpenLayers fed by JSON.
You'll need to find a way to reduce the point count in a smart way - like
feeding out a LOD (level of detail) algorithm.

Two or three years ago, people started looking for good ways to do this.
There might be an open source solution by now, but it would require
something more heavyweight than just OpenLayers.

_mpg

On Nov 12, 2013, at 7:06 AM, Eran Nevo <eran at utilis.co.il<mailto:eran at utilis.co.il>> wrote:

Oh , I'm looking for open source solution to show lidar on web application

On 12 בנוב 2013, at 16:40, Howard Butler <howard at hobu.co<mailto:howard at hobu.co>> wrote:

On Nov 11, 2013, at 12:21 PM, Eran Nevo <eran at utilis.co.il<mailto:eran at utilis.co.il>> wrote:

Hi there ,

Can anyone point me to an example how to implement PDAL with OpenLayers ?

I have LAS file and PostGIS db with points in them.

Want to try PDAL.

OpenLayers is a web JavaScript technology. PDAL is a data translation
software focused on transformations from one format to another. You could
try using PDAL to export point cloud data to GeoJSON (using
drivers.text.writer) and importing that into an OpenLayers map in some way.
You are very likely to overwhelm any browser, however, with any significant
amount of point cloud data.

Howard

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--
Roger Bedell
Coordinate Solutions Inc.
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