GNSS receivers

The lab have two high resolution GNSS receivers. The newest is a Trimble GeoXR 6000 from 2014 and the second is a TopCon GRS-1 from 2010. Both uses RTK (Real Time Kinematic) and connects to Swepos using either Telia cellular network or through a WLAN connection with a Net1-modem. Both these devices can measure a point in a few seconds with centimeter resolution, but it needs clear vision to the satellites.

Here are user instructions for the devices:

  • Trimble GeoXR 6000
  • TopCon GRS-1 (e-mail us if you need a copy, will be published shortly)
Measurement of a ground control point for a drone flight with the Trimble GeoXR 6000.
 

Computers

In the lab we have in total 8 computers specially designed to work with heavy processing of 3D-data. One of the computers is connected to a 75 inch UHD-TV and is used for presentations and the HTC Vive (Virtual Reality). One of the computers is stored in a server room and used as a processing machine.

The computers are numbered from their computer names:

  • 2019-65: Core i9 9980XE 3GHz (18-cores), 128 GB RAM, 2 x GeForece RTX 2080 Ti
  • 2017-1: Core i7 6800K 3.4GHz (6-cores), 64 GB RAM, 1 x GeForce GTX 1080 Ti, 2 x 25″ TFT 2560×1440
  • 2017-2: Core i7 6800K 3.4GHz (6-cores), 64 GB RAM, 1 x GeForce GTX 1080 Ti, 2 x 25″ TFT 2560×1440
  • 2016-36: Core i7 6700K 4GHz (4-cores), 64 GB RAM, 1 x GeForce GTX 1080, 75″ UHD-screen
  • 2014-98: Core i7 4930K 3.4GHz (6-cores), 64 GB RAM, 2 x GeForce GTX 780, 2 x 28″ UHD-screen
  • 2014-99: Core i7 4820K 3.7GHz (4-cores), 64 GB RAM, 1 x GeForce GTX 780, 2 x 27″ TFT 2560×1440
  • 2014-100: Core i7 4820K 3.7GHz (4-cores), 32 GB RAM, 27” 3D-screen
  • 2014-101: Core i7 4820K 3.7GHz (4-cores), 32 GB RAM, 27” 3D-screen

 

Terrestrial laser scanner

The lab has a Trimble TX8 laser scanner (from 2014). The scanner is used to collect accurate measurements of the ground and the tree stems. Here is an example of one birch that is cut out from a multiscan (several scans are merged into one dataset):

A birch consisting of 12 million 3D-points. This tree was cut from a larger area scanned with a terresterial laser scanner (TLS).

The scanner is mounted on a tripod and collects 1 million points every second. In three minutes a full scan is done with a point spacing of about 4 mm on 10 meters distance.

Multiscan where a sphere is mounted on the previous and the next scan location for georeferencing.
Example from a forest plot in Remningstorp. The points are colored by altitude and intensity.

Fly through video of a plot in Remningstorp. 16 scan locations merged. Intensity and height above ground are merged in the coloring of the 3D-points.

Fly through of another plot. Coloring of the 3D-points are from the intensity of each return.

 

LASTools

We have a research and education license for the LASTools software. It is installed in all the lab’s computers. Please contact the lab’s responsible if the license is experied or the program is missing. The tools are frequently updated so if you need the tools for your work, make sure you have the most recent version, please contact us if you notice that there is an old version installed (c:\lastools).

The latest version of LASTools can be downloaded from here. Read more about LASTools on RapidLasso GmbH.

Here is a summary of the tools available and also a few links where you can read more about the software and a active forum.

Open source tools

These tools does not require a license.

  • laszip.exe compresses the LAS files in a completely lossless manner
  • lasinfo.exe prints out a quick overview of the contents of a LAS file
  • lasindex.exe creates a spatial index LAX file for fast spatial queries
  • las2las.exe extracts last returns, clips, subsamples, translates, etc …
  • lasmerge.exe merges several LAS or LAZ files into a single LAS or LAZ file
  • txt2las.exe converts LIDAR data from ASCII text to binary LAS format
  • las2txt.exe turns LAS into human-readable and easy-to-parse ASCII
  • lasprecision.exe analyses the actual precision of the LIDAR points

Closed source tools

These tools requires the licence that we have installed in the lab’s computers.

  • lastool.exe is an old GUI for multiple LAStools (now each tool has its own GUI)
  • lasground.exe extracts the bare-earth by classifying all ground points
  • lasground_new.exe an improved version of lasground.exe for complex terrains
  • lasoverlap.exe checks overlap & vertical/horizontal alignment of flight lines
  • lascontrol.exe quality checks elevations for a list of control points
  • lasclassify.exe finds buildings and the vegetation above the ground
  • lascolor.exe colors the LAS points based on ortho imagery in TIF format
  • lasgrid.exe grids onto min/max/avg/std elevation, intensity, or counter rasters
  • lascanopy.exe computes many raster and plot metrics for forestry applications
  • lasboundary.exe extracts a boundary polygon that encloses the points
  • lasheight.exe computes for each point its height above the ground
  • lastrack.exe classifies LiDAR point based on distance from a trajectory
  • lasplanes.exe finds planar patches in terrestrial, mobile, (airborne?) scans
  • lasclip.exe clips points against building footprints / swath boundaries
  • lastile.exe tiles huge amounts of LAS points into square tiles
  • lassplit.exe splits points of LAS file(s) into flightlines or other criteria
  • lassort.exe sorts points by gps_time, point_source, or into spatial proximity
  • lasduplicate.exe removes duplicate points (with identical x and y, z optional)
  • lasthin.exe thins lowest / highest / random LAS points via a grid
  • las2tin.exe triangulates the points of a LAS file into a TIN
  • las2dem.exe rasters (via a TIN) into elevation/slope/intensity/rgb DEMs
  • las2iso.exe extracts, optionally simplified, elevation contours
  • lasview.exe visualizes a LAS file with a simple OpenGL viewer
  • las2shp.exe turns binary LAS into ESRI’s Shapefile format
  • shp2las.exe turns an ESRI’s Shapefile into binary LAS

BLAST extension (use if you have huge amount of points):

  • blast2dem.exe rasters like las2dem but with streaming TINs for billions of points.
  • blast2iso.exe contours like las2iso but with streaming TINs for billions of points.

Links

 

Drones

The lab has several drones designed for different loads and purposes. Here is a list of the models we have:

  • 1 DJI Phantom 4 RTK (2019)
  • 2 Quadrocopter drone, 3DR Solo (2016)
  • 1 DJI Phantom 4 pro (2017)
  • 1 DJI Mavic pro (2017)
  • 1 DJI Mavic 2 pro (2018)
  • 1 Smartplanes Freja

We also have equipment to be used with the drones, for example:

  • 20 Ground targets (black/yellow chess board). Measured with RTK-GNSS and pointed out in photos in photogrammetry software.
  • Spray paint for Ground Control Points (GCP).
  • RTK base station

Here are some of the drones in a field test:

 

Parrot Sequoia

Parrot Sequoia is a small and light weight (72 g) multispectral camera made for drones. The camera has a synchronus global shutter with four spectral bands:

  • Green (550 nm)
  • Red (660 nm)
  • Red edge (735 nm)
  • Near infrared (790 nm)

The camera also has an irradiance sensor (36 g) that can be mounted on top of the drone to measure the ambient light. The sensor also includes a GPS and IMU module and a SD-card slot.

We have mostly used the camera mounted on our 3DR Solo drone (mounting instruction).

3DR Solo drone. Under the drone is the Parrot Sequoia camera and on top is the irradiance sensor.

Here is an example of an ortophoto over a forested area close to a road and power-line in Remningstorp:

The spectral calibration plate for the lab looks like this. Use the information about the reflectance when postprocessing in for example Agisoft Metashape Pro or Pix4D.

 

Terrestrial laser scanning

Sample plots with 40 m radius were scanned with the Trimble TX8. Each sample plot was covered with 16 scan locations. In total 40 sample plots were scanned. The work was conducted from September to December 2014. Example of the data:

 

Remningstorp drone flights 2016

In August 2016 we collected drone images over the forest estate Remningstorp. This data collection was funded by “Stiftelsen för skogsvetenskaplig forskning” at the Swedish University of Agricultural Sciences. Below you find an overview of the flown areas. If you are interested to use one of the flight blocks, please contact Mattias Nyström. This data is free to use, but we might charge you a delivery cost depending on the amount of data.

We have made block25 available for direct download. This block was automatically post-processed using Agisoft Photoscan. The data is in SWEREF99TM RH2000, but is not georeferenced using ground control points. There has neither been any manual work done after the automatic batch processing. If you want to use the data for more than viewing and understanding, please contact us to receive the original photos and you may process the data yourself.

False color ortho photo automatically created from Sequoia photos taken over block25 in Remningstorp. Download the dataset form this link.

The following blocks were flown with the Parrot Sequoia multispectral camera:

remningstorp_droneimages_aug2016_overview_flight_blocks_sequoia
These blocks were collected with the multispectral camera Parrot Sequoia (pixel size 12 cm). Download the map as pdf or as geo-tif. The red border is the extent of the Remningstorp forest estate. © Lantmäteriet, i2014/764.

The following blocks were flown with the Sonya a5100 with a 20mm lens:

remningstorp_droneimages_aug2016_overview_flight_blocks_a5100
These blocks were collected with the RGB-camera Sony a5100 with a 20mm lens  (pixel size 3 cm). Download the map as pdf or as geo-tif. The red border is the extent of the Remningstorp forest estate. © Lantmäteriet, i2014/764.
 

Drone images, view on your screen

The data used to create this point cloud was collected using a drone flown at 60 m above ground. A GoPro Hero 3 camera with a modified lens was used to take the photos. The software Agisoft Photoscan Pro was used to generate the 3D points.

In the web-viewer, you can under “Material” change “Select Attribute” to “RGB” if you want to color the point by the color from the photos.

Open the viewer

 

Open lab every Wednesday

We now have “open lab” every Wednesday afternoon (13.00-16.00). At this time you can explore remote sensing data, use the lab’s sensors to collect data or follow one of our tutorials to learn how to work with remote sensing data. The tutorials is an ongoing work and will be published on the website as soon as they are ready for you. You can also ask questions to the lab’s forest remote sensing experts.

We also have a HTC Vive (Virtual Reality) that can be used to explore point clouds from mobile laser scanning, terresterial laser scanning and drone data.

Henrik visiting a forest in Virtual Reality.