In this article it is explained step by step how to use the Agisoft Ortho Mapping tool.
1. Introduction
For TrueView and DJI image sensors, the orthomosaic can be generated and the image positions and
orientations refined using Agisoft Ortho Mapping , that is included in an addon license to LP360
Drone, called Photo with Agisoft. Images may also be processed in the Cloud version for Ortho
Mapping using LP360 points purchased in the LP360 Store.
1.1. Pre-requisites
The Agisoft Ortho Mapping license is a separate key from the LP360 Drone+Photo with Agisoft licenses. See Licensing LP360 Drone+Desktop Photo with Agisoft for more information on activating/deactivating your Agisoft Ortho Mapping license. It is not necessary to install Metashape Pro to use this tool, however, Agisoft Ortho Mapping may also drive the GUI version of Metashape Pro (v1.7.1 through 2.0.x) if you have such licenses or desire to purchase a node-locked or floating license.
2. How to use Agisoft Ortho Mapping
When using a 3DIS (TrueView 3D imaging systems), it is recommended that you run a ground classification on your dataset and additionally classify any building roofs or bridge decks to achieve optimal and efficient results when running Agisoft Ortho Mapping to generate your orthomosaic.
- The active Cycle/Flight combination on the Sensor tab is not used by this utility, so it does not
matter what is selected. - Select Agisoft Ortho Mapping on the Sensor tab to open the Agisoft Ortho Mapping dialog. Note: To enable this tool requires a “Full Photo”, “Photo with Agisoft”, or “Photo3000” addon license be checked out in addition to the LP360 Drone license.
a) Input Settings
i. Available True Pose® Photo Layers – Select the checkbox in the “Use” column
beside all desired True Pose® layers that you wish to use as source photos for
the orthomosaic generation. This would typically include all RetainedPhotos
layers for every Cycle in the project that covers the desired area. A True Pose®
image means their full metadata, including camera calibration, is stored in
special GeoCue tags within each photo’s EXIF tags.
b) Processing Location
Select to process Local or Cloud by selecting the applicable radio button next to the option.
c) Metered Ortho Mapping
When Cloud is selected, this section will detail the number of photos, available LP360 Points, and the total cost for generating the orthomosaic using Ortho Mapping Cloud.
d) Output Settings
i. Apply a priori EO if BBA Fails (Only available if Orientation Quality >= INS) (Recommended for 3DIS®)
Always defaulted on for True Pose® photo layers
from a TrueView 3DIS®. This option is not available for DJI and other sensors.
When selected, two Metashape projects are generated as LP360 Drone
identifies those images for which Metashape failed to align, for instance, those
in vegetation, and updates the alignments for those in the new project. This
second project is then used to generate the orthomosaic so that the holes one
would normally have from a standard Metashape processing are minimized, if
not eliminated.
ii. Generate Ortho from DEM (Highly recommended for 3DIS®)
1. Input DEM Layer
a. Remove any high and low noise from the dataset. Often best accomplished using the Clip Range option in Geocode LiDAR, Low/Isolated PCT, and/or a Basic Filter PCT that uses elevation clipping. See Noise Removal Options for more details.
b. Run a ground classification (Adaptive TIN Ground PCT) against the dataset using appropriate settings for a good, generalized ground surface. It is not important to have a perfect surface as there is some leeway in the orthomosaic process, however, if you have features such as retaining walls then you may need breaklines to properly hold those types of features.
c. Optional - Manually cleanup the gross blunders in the ground surface (Class 2) using the manual classification tools found on the Classification tab and Profile toolbar, and/or the Ground Cleanup Filter PCT.
d. Optional - Manually classify building roofs to class 6, and bridge decks to class 17 to create a better looking orthomosaic.
e. Optional – To create the cleanest edge lines along buildings and bridges, polygonate the building and bridge deck classes, then set those to the ground and upper surface elevations by following these steps to create two polygon sets, one set being the buffered footprints and one set the headprints:
i. Use the Point Group Tracing and Squaring PCT with appropriate parameters for your dataset to polygonate the desired non-ground features, normally roofs and bridge decks, but could be other features desired for a “True Ortho”. To run this PCT with high density TrueView data you will first need to thin the dataset to roughly 8 points/m2 using the Classify by Statistics PCT.
ii. Use the Conflate PCT to pure drape a copy of each nonground feature to the ground class to create the footprints. This holds the edge clean to the existing ground surface.
iii. Use the Conflate PCT to conflate to the closest elevation of the building or bridge deck points found therein, a copy of each footprint polygon to create the headprints.
iv. We need to buffer the footprint polygons slightly, say 2.5cm, using the Buffer Geometry tool found on the Feature Edit tab, since in a TIN you cannot have two points at the same planimetric location with differing elevations.
v. Use the Classify by Feature PCT to mark any ground points found within the buffered footprint polygons so as not to use them in your resulting DEM.
vi. If you perform these steps to generate a set of buffered footprint polygons (buffered and ground conflated polygons) and headprint (closest elevation conflated) polygons for your desired non-ground features, then skip the Classify by Statistics PCT in the next step since you will not have conflicting surfaces over the same cell. Furthermore, use Breakline Enforcement, using the polygons generated by the preceding steps to help hold the edge of your features, when in the export DEM step.
f) Export a DEM using the Export Wizard to quickly create a DEMfrom the LiDAR data and generate the orthomosaic much faster than Metashape generating a DEM from the images.
i. Run Classify by Statistics PCT – For best results, it is recommended to perform some initial classification as described above before exporting a DEM. Run the Classify by Statistics PCT with the following recommended settings to help in areas where there are two surfaces in the same location, such as when the roof overhangs and the LiDAR sees the ground beneath:
1. Feature Geometry – Tool Geometry
2. Units – Set to project units.
3. Input LAS Layer – Active LAS Layer
4. Source Points - Classes 2, 6, and 17. Flags
ignored.
5. Cell Size – 0.05m - Gently rolling terrain doesn’t
need as high a resolution DEM as an area with
sharper features.
6. Samples – Max
7. Destination Class – Flags Only – Synthetic – Set
8. Quartile Classification – Leave blank.
9. Generate Cell Output Shape file – Leave
unchecked.
10. Run by project.
ii. Recommended Export LiDAR Data DEM settings:
1. Source Points:
a. If the Classify by Statistics in the previous section was performed, use Synthetic Flag Set
b. If the optional non-ground polygons were created and the Classify by Statistics PCT skipped, then use classes 2, 6, and 17 ignoring the synthetic flag.
c. or use all points for a quick ortho.
2. Export Type - Surface
3. Surface Method - Triangulation
4. Pixel size: 0.05m to 0.25m. Gently rolling
terrain does not need as high a resolution DEM
as an area with sharper features.
5. Surface Attribute to export – Elevation
6. Export Format – GeoTIFF
7. Raster Information – Pixel Size: 0.05 to 0.25m. Gently rolling terrain doesn’t need as high a resolution DEM as an area with sharper features.
iii) Generate Point Cloud / Ortho from Images - Typically only use this option for
2DIS (image only systems). This option will take much longer and will generate
a Dense Image Matching (DIM) point cloud.
1. Generate Point Cloud (LAS) - generate and retain the Dense Image Matching (DIM) point cloud to add to the project during the postprocess step.
2. Generate Ortho - generate and retain the orthomosaic to add to the project during the post-process step.
iv) Bundle Block Adjustment (BBA) Only – Useful for troubleshooting, or to
improve the True Pose® information for use with Image Explorer when not
generating an orthomosaic.
e) Output Point Cloud – Only use this option for 2DIS (image only systems)
i. Create New LAS Layer - LAS Layer Name – Type in a unique name for the destination layer on which to generate the DIM LAS files from the Ortho Mapping run.
ii. Append to Existing LAS Layer – Select from the Available LAS Layer the previously created layer name on which to append the additional DIM LAS files.
f) Output Ortho
i. Create New Ortho Layer – Ortho Layer Name – Type in a unique name for the
destination layer on which to generate the orthomosaic raster resulting from
this Ortho Mapping run.
ii. Append to Existing Ortho Layer – Select from the Available Ortho Layers a
previously created layer name on which to add the orthomosaic raster resulting
from this Ortho Mapping run.
g) Advanced Settings – Opens the Agisoft Ortho Mapping Advanced Settings dialog
h) Submit Ortho Mapping Job – Submits the Agisoft Ortho Mapping processing to the Job Manager queue for processing.
3. A successfully submitted job notification will appear confirming the job submission
4. An e-mail will be sent when the processing begins to the e-mail configured in the LP360 e-mail Notification Settings (File -> Project Settings -> Global -> LP360 E-mail Notification Settings).
5. The Agisoft Ortho Mapping job progress may be monitored using Job Manager.
6. Upon completion of the Agisoft Ortho Mapping job by the Job Manager.
7. In Job Manager, select the applicable Agisoft Ortho Mapping job, then select View Report to review the Agisoft Ortho Mapping processing report. Review for position and orientation average corrections to be within tolerances for your system’s POS.
8. If desired, or for troubleshooting, in Job Manager, select the applicable Agisoft Ortho Mapping job, then select View Log to review the Agisoft Ortho Mapping processing log.
9. In Job Manager, select the applicable Agisoft Ortho Mapping job, then select Open Project to open the applicable project for the job, if not currently open.
10. Then, select Post-Process to add the new Ortho Layer and/or raster file, and for 2DIS the new LAS Layer and/or LAS file(s) to the currently open project based on the settings at the time the job was submitted. Plus, update the EXIFs on each photo to the bundle block adjusted values.
a) If the run location selected was Cloud, you will be asked to browse for the 7z file you downloaded from the link in the job completion e-mail.
11. Review the generated Orthomosaic and for 2DIS, LAS data.
12. When desired, in Job Manager, select the applicable Agisoft Ortho Mapping job, then select Delete Job to clean up the temporary files generated while processing the job.
13. Optional: Use the Reproject Raster PCT providing it your deliverable project boundary, or boundaries if you would like to tile the ortho, as input geometry, leave the reproject unchecked so as not to reproject the raster, and it will quickly create you a clipped orthomosaic. This PCT is also useful for converting the Ortho Mapping generated orthomosaic from the default BigTIFF format to a regular TIFF for using the raster in Autodesk’s Civil3D, which cannot read BigTIFFs. Unless, of course, your orthomosaic is around 4GB or larger, thus requiring to be a BigTIFF, unless you use the Reproject Raster PCT to cut the orthomosaic into an index of your own or one created using the Grid Generator PCT.
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