Monday, July 25, 2016

Assign a coordinate reference system to a LiDAR las file using PDAL

Some of the LiDAR las files I receive do not contain embedded coordinate reference system (CRS) tags. It would be nice to be able to set a CRS tag to the las file so that I don't have to choose a coordinate reference system everytime I load the file; and I found the Point Data Abstraction Library (PDAL) to have the tools to do exactly that.

To use PDAL to assign a CRS to a las file, do the following:

  1. Open up a Command prompt. Type in the pdal command:

    C:\> pdal translate -i input.las -o output.las --writers.las.a_srs="EPSG:32750"

    Note: where a_srs is the option to assign a CRS e.g. EPSG:32750

  2. To double check whether the CRS tag has been assigned to the las file, you can use the lasinfo tool from liblas, as shown below.


Monday, July 18, 2016

Volcamr New Zealand - Android app for viewing NZ's volcano webcams

Use this Android app to download and display the latest volcano camera still images from New Zealand's GeoNet at http://www.geonet.org.nz/. The following volcanoes can be monitored through the remote webcams: Ruapehu, Ngauruhoe, Tongariro, White Island and Taranaki.
The webcam locations are indicated as clickable markers on a Google Maps backgroud as shown below. 

Download and install this app from the Google Play Store.
Get it on Google Play

Monday, July 11, 2016

Google Mapplet for displaying Earth Centered, Earth Fixed (ECEF) coordinates

The ECEF (Earth-Centered, Earth-Fixed) coordinate system is commonly used when working with satellites, GPS, space mechanics. For more information, see the Wikipedia site at https://en.wikipedia.org/wiki/ECEF. Sometimes, it may be necessary to convert between ECEF coordinates to geodetic latitude, longitude and altitude coordinates.

This Google Mapplet Show ECEF Coordinates is an easy to use tool for displaying ECEF coordinates on a Google Maps background. To show the coordinates of a location on the map, just click a point on the map, as shown in the screenshot below.

Alternatively, given an ECEF coordinate, simply type in the ECEF's XYZ coordinates in the right pane and click the Locate button. The point will be centered and marked in the map display, as shown below.

Try on this tool at this location https://dominoc925-pages.appspot.com/mapplets/cs_ecef.html


Monday, July 4, 2016

Set up Visual Studio to use the All-in-one Point Cloud Library PCL

Point Cloud Library (PCL) from http://pointclouds.org is a powerful library for working with point clouds. But the downloadable binaries are outdated and compiling the latest source code can be a bit of a pain. Fortunately, you can get more recent all-in-one PCL binaries from this blog site http://unanancyowen.com/?p=1255&lang=en for use in your projects.

Installing PCL All-in-one

  1. Just follow the instructions on the site to download and install a version of PCL e.g. PCL 1.7.2 All-in-one Installer MSVC2015 X64, for your development environment.
  2. Also download a suitable Visual Studio property sheet e.g. PCL Property Sheet, and save the file on your machine as e.g. pclPropertySheet.props.
  3. After installing, add the bin folder locations of PCL and VTK to the Windows PATH environment variable, as shown below.

Setting up Visual Studio
  1. Run Visual Studio. Select File | New | Project.
    The New Project dialog appears.

  2. Select Templates | Visual C++ | General. Choose Empty Project. Type in a project Name e.g. HelloPCL. Browse to a Location. Click OK.

    The project is created.

  3. In the top right pane, click the Property Manager tab.

    The Property Manager tab is activated.

  4. Click the Add Existing Property Sheet icon, as shown above.
    The Add Existing Property Sheet dialog box appears.

  5. Browse and select the previously downloaded property sheet e.g. pclPropertySheet.props. Click Open.

    The property sheet is loaded.
  6. Now create a new C++ source file, e.g. main.cpp.



  7. In the C++ file, type in PCL include header file(s) and classes, as shown below.




  8. Optional: the PCL headers and classes may display wavy red under lines. If so make sure you are working in the correct configuration. In this example, the environment is for x64. Change the configuration to x64 from x86.

    Visual Studio now recognizes the PCL headers and classes
    .

Monday, June 27, 2016

Trainsity Kuala Lumpur Windows Phone app

Carry these high resolution vector maps of Kuala Lumpur's LRT, KTM, and other train lines in your Windows Mobile handset and find your way around Kuala Lumpur. The maps are small in file size and can be accessed offline without a data connection. The following lines are available:

  • Monorail
  • Ampang Line
  • Sri Petaling Line
  • Kelana Jaya Line
  • KTM Lines
  • KLIA Lines


Users can click the train station labels to open the external Bing Maps app where they can use all the functions of the external app to visualize the surrounding area including querying for directions. This app has its own directions function for finding the best path from one train station to another.

On a Windows Mobile handset,  the app will display tiles of train lines, which when tapped will open up a detail view of the metro transit map, as shown below.
Tapping the station labels will bring up an option menu where users can choose to display the station location in Bing Maps.

If you want to find how long it takes to travel from one station to another, and the best route to take, simply swipe to the Route page. Then type in the From station and To station. As you enter the values, a drop down list will appear and a station can be selected from the list.
Finally tap the Execute icon. 
Tapping the more details link will display the recommended route to take.
Click the badge below to download from the Windows Store.
Get it from Microsoft

Monday, June 20, 2016

Trainsity Hong Kong Windows Phone App

Find your way around Hong Kong city's subway using the high resolution vector maps of the train network. The following metro rail lines are available: East Rail, Kwun Tong, Tsuen Wan, Island, Tung Chung, Airport Express, Tseung Kwan O, West Rail, Ma On Shan, and Disneyland Resort lines.

The maps have small file size footprints but with many levels of zoom and can work offline without connecting to the Internet. Users can click the train station box labels to open Bing Maps, where they can use all the functions of the external app to visualise the surrounding area and/or perform routing for directions.

There is also an offline function to calculate the best way to travel from a station to another station with a direction breakdown and timings (which may vary from the actual travelling time).

On a Windows Mobile 8+ handset, the app will display tiles of train lines, which when tapped will open up a detail view of the metro transit map, as shown below.
 
Tapping the station labels will bring up an option menu where users can choose to display the station location in Bing Maps.


If you want to find out how long it takes to travel from one station to another, and the best route to take, simply swipe to the Route page. Then type in the From station and To station. As you enter the values, a drop down list will appear and a station can be selected from the list. Finally, tap the Execute icon.

Tapping the more details link will display the recommended route to take.

Click the button below to download the app from the Windows Store.
Get it from Microsoft

Monday, June 13, 2016

Use PDAL to merge multiple LiDAR las files

I found a useful tool, something that works along the lines of GDAL for vector data, but for point cloud data; it's the Point Data Abstraction Library (PDAL).  PDAL can be downloaded from http://www.pdal.io/. It has some useful commands, like merging LiDAR las files, which I tried to use, as an alternative to other tools like Lastools.

Using PDAL to merge a few las files is straightforward, as illustrated below. If there are hundreds of las files to zip, then another tool might be more suitable.


To use PDAL to merge las files, just type in the following command at the Command prompt.
C:> pdal merge --verbose=5 part_1.las part_2.las part_3.las output.las


Note I: all the input las files will be merged into the last file name in the command.
Note II: the --verbose option tells the command the amount of processing messages to display. 0 for none. 
The resultant merge file is shown below.
Related Posts with Thumbnails