Lear how to combine imagery and lidar data for 3D feature extraction with ArcGIS, for aerial, mobile and terrestrial laser scanning

1. LiDAR and Stereo Imagery
Aldo Facchin – Geosoft Srl (Italy)
www.geosoft.it

2. Geosoft Srl - Italy
Who we are ?
 An italian company focused on software products for …
• Map production
• 3D photogrammetry
• LiDAR
• Mobile Mapping (from vehicle)
 Founded in 1992
 Main markets (last 3 years) :
• 70-85 % Map, Survey and Engineering industry
• 15-30 % Public Administration, University and Research

3. Geosoft Srl - Italy
Our offer…
A family of ArcGIS Desktop stereoscopic extensions for :
 Aerial photogrammetry and lidar (with a patented method)
 Terrestrial Laser Scanning
 Mobile Laser Scanning

4. Aerial Stereo Imagery and Lidar
ArcGDS Stereo + LiDAR extension

5. Aerial Stereo Imagery and Lidar
Photogrammetry and Lidar are better if combined
Photogrammetry (3D imagery) alone is
not enough…
 Optimal photointerpretation (image data
is continuous)
 Use of RGB, CIR images with 8+ bit per
channel
 Already experienced operators, well
known procedures and system
New digital cameras have bad B/H ratio
so Z quality is poor (respect to the
LiDAR data at the same
flight height)
Data quality is not geometrically
constant (Z in particular) because
depends on the operator (stereoscopic
perception)
Image correlation often have problems
exactly where we need (for ex. roof
edges)

6. Aerial Stereo Imagery and Lidar
Photogrammetry and Lidar are better if combined
LiDAR alone is not enough…
 Optimal precision (especially Z) respect
to the photogrammetry at the same flight
height
 Possibility to classify the points cloud
 Data quality is geometrically constant
(Z in particular) because does not
depend on the operator (snap)
 Data have low costs and short
acquisition times
Interpretation is very poor because the
data is discrete
Point density impacts a lot on cost
The points don’t have directly the color
of the objects
XY precision is poorer than Z

7. Aerial Stereo Imagery and Lidar
Photogrammetry and Lidar are better if combined
The solution :

8. Aerial Stereo Imagery and Lidar
Photogrammetry and Lidar are better if combined
The solution :
 The operator move the cursor
observing the imagery stereo scene
 The software update the cursor
height according with the point cloud,
using different alghoritms
 Stereo imagery are used for XY and
photointerpretation
 LiDAR point clouds are used for updating collimation mark
height (Z)
 The point cloud is better than using DSM or other
resampled products
 The operator has only the “check” the collimation
mark height (Z), not directly and carefully position it !

9. Live demo
ArcGDS Stereo + LiDAR extension

10. Aerial Stereo Imagery and Lidar
Photogrammetry and Lidar are better if combined
Characteristics of ArcGDS LiDAR method (patent pending)
It’s a tool for the production of high quality 3D geodatabases.
 Photointerpretation is available (photos, 3D...not orthophoto)
 LiDAR acquisition allow much better Z precisions than photo-
mapping or orthophoto digitalization
 Mapping (for ex. streets or buildings) is coherent with LiDAR
 Operator checks Z during mapping and eventually changes it
manually
 Is for everybody because not require a high photogrammetric
experience
 Snap uses cloud classification
 Transversal profile view helps operator for a better interpretation
Operator must control contemporary 3 windows

11. Aerial Stereo Imagery and Lidar
Photogrammetry and Lidar are better if combined
Key concepts :
 Stereoscopy is for avaiable for all the users at low cost, inside ArcMap,
for images and point clouds
 The time of proprietary CAD platform for maps data capture is over !
 Combine stereo images and LiDAR point clouds to obtain the best
accuracy and efficiency
 It’s the ideal tool for QC/QA after automatic feature extraction
phase
 Can be bundled with raw data (images & point cloud) by data
providers
 With this (patented) method…
• medium format cameras can be used
• low density point clouds can be used

12. Terrestrial Laser Scanning
ArcGDS for TLS

13. Terrestrial Laser Scanning
Use 3D glasses to save time, use images and point clouds as they are
During 3D feature extraction from laser scanner point clouds…
 Operators spend a lot of time on moving and rotating the
scene
 It’s easy to do mistakes on snapping laser point of different
planes
 Often the images are used only to color the points
The proposed solution :
 Try to use 3D glasses to watch your point cloud !
 Save time because you see your scene in 3D… don’t need
to continue to rotate
 Use images “as images”

14. Terrestrial Laser Scanning
Use 3D glasses to save time, use images and point clouds as they are
The solution :

15. Terrestrial Laser Scanning
Use 3D glasses to save time, use images and point clouds as they are
 The left view can be observed in 3D, rotated, zoomed, etc.
 In the right view an image can be loaded to show the current
cursor position
 Riegl V-line scanner are directly supported
 Leica Scanstation C-10 internal camera support is under
development
 Any oriented image can
be loaded
 Collecting data inside a
geodatabase is the best
benefit !
 Multiuser, versioning, etc.
are avaiable also in TLS
 Why use a CAD ?

16. Live demo
ArcGDS for TLS

17. Mobile Laser Scanning and Imagery
ArcGDS for MLS

18. Mobile Laser Scanning
Use video to quickly navigate and 3D stereoscopic vision accurate data
collection
Now…
 The current trend on MLS is to do all the work
using laser scanner(s) point cloud
 The camera(s) are only for give color to point
cloud
 Do you think to handle a mobile laser scanning
road network project with a CAD ?

19. Mobile Laser Scanning
Use video to quickly navigate and 3D stereoscopic vision accurate data
collection
Our idea…
 Try to use camera image sequences (video) to
quickly navigate…
 Use the point cloud only for the 3D precise
measure task
 Use the images to recognize the objects you
have to collect
 Use 3D glasses to save time

20. Terrestrial Laser Scanning
Use 3D glasses to save time, use images and point clouds as they are
The interface :

21. Live demo
ArcGDS for MLS

22. Conclusion
 Images don’t replace point clouds and vice-versa
 Use the best of each data type
 Combine them
 GIS is necessary for a good data collection
• for multiuser handling
• for versioning
• for data consistency
• etc.
 There are no more advantages on using CAD for
3D

23. Thank you !
Grazie !
aldo.facchin@geosoft.it
For further information, please visit Esri booth
at SPAR International 2011.