ArcGIS Add-in Development In Python and C# for LIDAR Product Quality Control
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The document describes ArcGIS add-ins developed by David Eliseo Martinez Castellanos for the Salvadoran Ministry of Environment and Natural Resources to assist in quality control of LIDAR data for El Salvador. Tools include loaders to import LAS tiles into a PostgreSQL database with quality metrics, toolbars to evaluate tiles against criteria, and editors to mark defects on products. The tools were created with Python and C# for use in ArcGIS and integrate with the database for automated and manual quality reviews.
![Background: El Salvador’s LIDAR survey
“Digital elevation data which describes El Salvador’s landforms and seabed is crucial for
addressing issues relating to the impacts of climate change, disaster management, water
security, environmental management, urban planning and infrastructure design.”
“The intent of this project is to support MARN throughout the El Salvador National Territory with
more accurate data by the generation of Digital Elevation and Surface Models using the Laser
Imaging Detection and Ranging (LIDAR) technology, and with multi-spectral orthoimagery. The
project requires the collection and delivery of high-density LIDAR data and digital imagery for
the totality of El Salvador.”
From El Salvador National Lidar & Orthophotography Specifications and Tender Template.
To help in the Quality Control Workflow of the LIDAR Survey, some software tools where
developed, including ArcGIS Add-ins, using both Python and the ArcObjects .Net SDK with
C#, this tools are integrated with a PostgreSQL Database.
The complete Quality Control methodology will be documented later, here we talk about
the tools [my participation].](https://image.slidesharecdn.com/arcgisaddindevelopment-141217150330-conversion-gate01/85/ArcGIS-Add-in-Development-In-Python-and-C-for-LIDAR-Product-Quality-Control-2-320.jpg)
![Check Toolbars
For each product there is a toolbar with a dropdown selection for each criteria.
GIS technician selects if the product complies or not with the evaluation criteria.
This information is stored un the database, including the id of the technician and
revision time [tools also developed in Python]](https://image.slidesharecdn.com/arcgisaddindevelopment-141217150330-conversion-gate01/85/ArcGIS-Add-in-Development-In-Python-and-C-for-LIDAR-Product-Quality-Control-5-320.jpg)
![Check Toolbars
Each LIDAR product has its own check toolbar, showing the criteria to be evaluated by
a GIS Technician, the database contains more criteria for each product that are
automatically checked by a program [cell size, data type, spatial reference, etc.]](https://image.slidesharecdn.com/arcgisaddindevelopment-141217150330-conversion-gate01/85/ArcGIS-Add-in-Development-In-Python-and-C-for-LIDAR-Product-Quality-Control-6-320.jpg)
![LAS information [header and statistics] Query Tool
Allows user to query the
LAS header and statistics
from the database.
Retrieves information for
the current selection.
The component is a
dockable window
developed with
ArcObjects .Net SDK
using C#.](https://image.slidesharecdn.com/arcgisaddindevelopment-141217150330-conversion-gate01/85/ArcGIS-Add-in-Development-In-Python-and-C-for-LIDAR-Product-Quality-Control-7-320.jpg)
![LAS information [header and statistics] Query Tool
The tool allows to query
the results of automatic
revision criteria,
[complies, no complies]
retrieving LAS header
and statistics and
selecting the
corresponding tiles, this
can be combined with
the loader tool for
further check of such
tiles.](https://image.slidesharecdn.com/arcgisaddindevelopment-141217150330-conversion-gate01/85/ArcGIS-Add-in-Development-In-Python-and-C-for-LIDAR-Product-Quality-Control-8-320.jpg)
![LAS information [header and statistics] Query Tool
The tool allows query by
SQL WHERE definition,
returning LAS header and
statistics and selecting the
corresponding tiles. The
example shows the results
for “classes like ‘%(9)%’”](https://image.slidesharecdn.com/arcgisaddindevelopment-141217150330-conversion-gate01/85/ArcGIS-Add-in-Development-In-Python-and-C-for-LIDAR-Product-Quality-Control-9-320.jpg)
![LAS information [header and statistics] Query Tool
The tool also allows
the selection of the
fields to return on
the result.](https://image.slidesharecdn.com/arcgisaddindevelopment-141217150330-conversion-gate01/85/ArcGIS-Add-in-Development-In-Python-and-C-for-LIDAR-Product-Quality-Control-10-320.jpg)
ArcGIS Add-in Development In Python and C# for LIDAR Product Quality Control
- 1. ArcGIS Add-in Development In Python and C# for LIDAR Product Quality Control Tools Developed by David Eliseo Martínez Castellanos For The Salvadoran Ministry of Environment and Natural Resources (MARN)
- 2. Background: El Salvador’s LIDAR survey “Digital elevation data which describes El Salvador’s landforms and seabed is crucial for addressing issues relating to the impacts of climate change, disaster management, water security, environmental management, urban planning and infrastructure design.” “The intent of this project is to support MARN throughout the El Salvador National Territory with more accurate data by the generation of Digital Elevation and Surface Models using the Laser Imaging Detection and Ranging (LIDAR) technology, and with multi-spectral orthoimagery. The project requires the collection and delivery of high-density LIDAR data and digital imagery for the totality of El Salvador.” From El Salvador National Lidar & Orthophotography Specifications and Tender Template. To help in the Quality Control Workflow of the LIDAR Survey, some software tools where developed, including ArcGIS Add-ins, using both Python and the ArcObjects .Net SDK with C#, this tools are integrated with a PostgreSQL Database. The complete Quality Control methodology will be documented later, here we talk about the tools [my participation].
- 3. Database Support As part of the tool Development to support the Quality Control of the LIDAR products, a Database was build on a PostgreSQL Server with PostGIS Spatial Extension. This database stores: • The geometries of sample LAS tiles received • A table of the storage path of each tile, to be used on a loader tool. • LAS header and statistics for each tile • Tables to store the results of quality control for each product and each tile. Some of the quality control criteria are evaluated by programs (automatic check) and some are evaluated by a GIS technician. • Spatial table to store polygons to be drawn over defects on the LIDAR products.
- 4. Loader tool Each GIS technician is provided with a tiles shapefile containing the set of tiles to be checked and the set of LIDAR products corresponding (DEM, DSM, LAS, etc.). The tool allows the graphical selection of the product to check. This tool was developed using Python
- 5. Check Toolbars For each product there is a toolbar with a dropdown selection for each criteria. GIS technician selects if the product complies or not with the evaluation criteria. This information is stored un the database, including the id of the technician and revision time [tools also developed in Python]
- 6. Check Toolbars Each LIDAR product has its own check toolbar, showing the criteria to be evaluated by a GIS Technician, the database contains more criteria for each product that are automatically checked by a program [cell size, data type, spatial reference, etc.]
- 7. LAS information [header and statistics] Query Tool Allows user to query the LAS header and statistics from the database. Retrieves information for the current selection. The component is a dockable window developed with ArcObjects .Net SDK using C#.
- 8. LAS information [header and statistics] Query Tool The tool allows to query the results of automatic revision criteria, [complies, no complies] retrieving LAS header and statistics and selecting the corresponding tiles, this can be combined with the loader tool for further check of such tiles.
- 9. LAS information [header and statistics] Query Tool The tool allows query by SQL WHERE definition, returning LAS header and statistics and selecting the corresponding tiles. The example shows the results for “classes like ‘%(9)%’”
- 10. LAS information [header and statistics] Query Tool The tool also allows the selection of the fields to return on the result.
- 11. QC Editor: ArcMap Custom Editor developed for the Quality Control process As part of the QC Process GIS technicians are required to mark the areas where there is a defect on the products. Initially this was done using the standard Editor toolbar, but to simplify the work for the technician a custom Editor was made for the QC shapefile and also stores the data in the database including geometries.
- 12. QC Editor: ArcMap Custom Editor developed for the Quality Control process When the user presses the apply button, changes are simultaneously applied to the local shapefile and the database server. This tool was also developed using ArcObjects .Net SDK with C#
- 13. What is next? The project is currently on going. User feedback is expected and we will look for ways to improve the process. Next is the development of tools to manage all data products and make them accessible to Salvadoran people, decision makers, planners, etc. More is to come. THANKS! David Eliseo Martínez Castellanos Software Developer MARN El Salvador eliseo.martinez@gmail.com emartinez@marn.gob.sv Linked-in: sv.linkedin.com/pub/david-eliseo-martinez-castellanos/35/71b/7b5/