Data Collection Details
Lidar Scans and Panoramic Images
scans and panoramic images were
acquired at 37
different locations on Devon Island with an Optech ILRIS3D-ER. The
point clouds from these 360° scans contain millions of points
spread out over a maximum range of about 1.5km with centimeter-scale
position accuracy. A camera on the lidar also allowed panoramic images
to be collected. Before each scan, the lidar was leveled with a
two-axis bubble level to an accuracy of about 1 degree for one standard
deviation. To obtain the heading of the lidar with respect to the
Easting, a target was setup about 100 metres away and scanned. Knowing
the GPS locations of the target and lidar, the orientation of the lidar
could be determined with an accuracy of 1 degree for one standard
Ground-truth positions of the lidar scan locations were
obtained from a
Garmin GPSMAP 76CSx. After averaging GPS measurements for several
minutes at each scan location, the standard deviation of position
measurements was estimated to be 1m.
The date and time of each scan are given in the following table. Each scan took at least 30 minutes to collect so we report the time that the scan was started in Central Daylight Time (CDT). The start times are accurate to within 30 minutes.
|Scan|| Date || Start Time (CDT) |
|A01|| July 18, 2008 || 10:49 |
|A02|| July 18, 2008 || 13:56 |
|A03|| July 18, 2008 || 15:15 |
|A04|| July 18, 2008 || 16:36 |
|A05|| July 18, 2008 || 17:41 |
|A06|| July 17, 2008 || 17:43 |
|A07|| July 17, 2008 || 16:35 |
|A08|| July 17, 2008 || 15:32 |
|A09|| July 17, 2008 || 14:23 |
|A10|| July 17, 2008 || 13:18 |
|A11|| July 17, 2008 || 12:21 |
|A12|| July 17, 2008 || 11:17 |
|A13|| July 14, 2008 || 17:12 |
|A14|| July 14, 2008 || 15:50 |
|A15|| July 14, 2008 || 14:48 |
|A16|| July 14, 2008 || 13:41 |
|A17|| July 14, 2008 || 12:12 |
|A18|| July 14, 2008 || 10:09 |
|A19|| July 13, 2008 || 17:17 |
|A20|| July 13, 2008 || 15:56 |
|A21|| July 13, 2008 || 13:32 |
|A22|| July 13, 2008 || 10:43 |
|A23|| July 13, 2008 || 12:04 |
|A24|| July 10, 2008 || 13:23 |
|A25|| July 10, 2008 || 15:48 |
|A26|| July 21, 2009 || Unknown |
|A27|| July 21, 2009 || 10:25 |
|A28|| July 22, 2009 || 11:14 |
|A29|| July 23, 2009 || 11:01 |
|A30|| July 24, 2009 || 11:09 |
|A31|| July 24, 2009 || 14:51 |
|A32|| July 24, 2009 || 11:05 |
|A33|| July 25, 2009 || 11:12 |
|A34|| July 25, 2009 || 12:56 |
|A35|| July 27, 2009 || 16:38 |
|A36|| July 28, 2009 || 12:24 |
|A37|| July 28, 2009 || 17:30 |
Orbital maps of Devon Island were obtained on
December 11, 2009
repository of up-to-date geospatial data for Canadian
Canadian Council on Geomatics. The maps were
projected from North American Datum 1983 (NAD83)
latitude/longitude coordinates to the Universal
Transverse Mercator (UTM) coordinate system using the
Mapper. The elevation data in the maps is
expressed in the Canadian Geodetic Vertical Datum 1928
(CGVD28). Two maps are provided:
- a 1:50,000 high-resolution map with each pixel covering an area approximately 12.5 x 25 meters. This was derived from Geobase maps ``058h06'' and ``058h07'', and
- a 1:250,000 low-resolution map with each pixel covering an area approximately 50 x 100 meters. This was derived from Geobase map``058h''.
File Format and Description
The dataset is organized into two subsets:
The files contained in these subsets are further described below.
- Lidar Scans: 3D lidar scan point clouds, panoramic
images and ground-truth UTM scan locations,
- Orbital Maps: 3D maps of relevant areas of Devon
Lidar Scan Point Cloud
Filename: A[Scan #].txt
This file contains a 3D point cloud obtained from the scan at position
[Scan #] in the following format:
||Intensity [no units]
where the coordinate frame origin is at the laser center,
the x-axis points East, the y-axis points North,
the z-axis points up, and the reflected beam's intensity ranges
from 0 (weak) to 255 (strong).
Lidar Scan Panoramic Image
Filename: A[Scan #].png
This file is a 360 degree panoramic image of the local terrain at scan
position [Scan #]. Each image has been cropped such that the rightmost
pixels coincide with the local Easting.
Lidar Scan Ground-Truth
Ground-truth UTM positions (all are UTM zone 16X) acquired from a
Garmin GPSMAP 76CSx in the following format:
Filenames: "mapHiRes.txt", "mapLoRes.txt"
These files contain orbital map data in UTM coordinates. The UTM zone
for these maps is 16X. They are provided in the following format:
|UTM x [m]
||UTM y [m]
Detailed map specification files are available from Geobase. The maps' respective
resolutions and accuracies (one standard deviation)
are given below:
||x Res. [m]
||y Res. [m]
||x, y Acc. [m]
||z Acc. [m]
Matching Scans To Orbital Maps
Lidar scans can be matched to the orbital maps to
globally localize the lidar scan origin. As given, the maps are much
larger than any individual scan. It may therefore be of interest to trim the
maps (see plotPointsOnMap.m) before attempting to match.
Scans 24, 25 and 29 are not fully contained by the
orbital map ( eg. try executing plotPointsOnMap(24,'mapHiRes')
). Data for this area of Devon Island is not currently available from Geobase.
Plotting Scan Points On Images
Scan points can be plotted on the panoramic images (see plotPointsOnImage.m)
knowing the lidar's camera parameters. The horizontal and vertical
fields of view of each image are respectively 360° and 45.5°.
East (0°) is the rightmost pixel. The middle vertical pixel is zero
degrees, with the exception of the following scans, which were tilted:
The dataset may be downloaded as a zip
Scans | compressed size: 1300MB, extracted size: 4480MB
Maps | compressed size: 33MB, extracted size: 312MB
Important note: The dataset provides ftp download links. Some browsers no longer enable ftp links by default and you need to change the settings if you want to download using the browser. Using the wget command is an alternative to avoid the browser.
The following tools are provided for the convenience of
dataset users. Run them in the dataset's root directory.
Matlab Scripts (zip file)]
- loadGroundtruth.m Loads UTM position
ground-truth for a scan into Matlab variables.
- loadOrbitalMap.m Loads an orbital map
into Matlab variables.
- loadScanPoints.m Loads point clouds
of scans into Matlab variables.
- plotPointsOnImage.m Plots horizon
scan points onto a panoramic image.
- plotPointsOnMap.m Plots scan points
onto an orbital map.