Multi-Cycle Processing Tips

For a lot of project areas, it is necessary fly multiple Cycles to cover the project area. Follow these tips to help process multi-Cycle projects efficiently.

• Import all Cycles that cover the project area into the same LP360 project.
• Use Project Manager to build Cycle and Temporal layer groups.
  • Open Project Manager .
  • Change Groups mode to Build.
  • Use  to automatically create layer Groups for each unique Cycle and Temporal date included in the project.
• Use the Cycle layer groups to help move from Cycle to Cycle to process in a methodical manner through to colorized point clouds for 3DIS®, and updated EXIF tags for all systems.
  • Open Project Manager .
  • With Groups mode set to Use, select the desired Cycle Group from the available Groups in the left pane. The layer group shown in the TOC will change as you select a different group in Project Manager. When only one Cycle is in a layer Group, the Cycle selector on the Sensor tab automatically changes to match. You may leave Project Manager open to make it easier to change between groups, or close and re-open as needed.

Figure 1 - Selected Layer Group being displayed in the TOC

• It is typically best to QC the individual Cycle LAS layers before merging as it is easiest to correct or make elevation adjustments when the Cycles are separated. If using Strip Adjustment or Strip Align , you probably do not need to make any elevation adjustments to the individual Cycles but should still perform the QC.
  • You can do some manual comparisons of the Cycles to each other by toggling the active LAS layer while reviewing the profile and 3D View to compare.  
  • Run a control report of each Cycle LAS layer to your check points to see if there are any issues such as a large offset in one of the Cycles due to mistakes in the trajectory processing.
  • A quick review of the attributes and coverage of each LAS layer for any issues.
  • Use the Affine Transform LAS PCT to adjust any significant elevation offsets of lines or Cycles to better match when they are merged.

Note: For dual purpose 3DIS (drone + mobile), if your project requires merging aerial and mobile cycles, each method must have corrective post-processing steps performed prior to merging. This is necessary because both collection methods will produce different GNSS biases. A typical workflow would be to run Strip Adjustment or Strip Align on all cycles together per respective collection method, then apply adjustments such as debiasing or Accuracy Star adjustments, then merge.

• For 3DIS®, when using Strip Adjustment , process all Cycle/Flight LAS layers into a single combined Strip Adjusted LAS layer by selecting all Cycle/Flight LAS layers when processing in Strip Adjustment .
  • If processing new flight(s) to add to already Strip Adjusted Cycles, set the already Strip Adjusted data as reference files (LAS or Cycles) and write the new results to a new LAS layer. This allows for scaling the workflow to larger projects where your system resources may not allow for processing all Cycles in a single run, or for times where you may be processing data blocks as they’re acquired and adding more over time.
• For 3DIS® or DJI L1/L2, when using Strip Align , process all Cycle/Flight LAS layers into a single combined Strip Align Adjusted LAS layer by selecting all Cycle/Flight LAS layers when processing in Strip Align .
  • If processing new flight(s) to add to already Strip Align adjusted Cycles, set the already Strip Align adjusted data as fixed and write the new results to a new LAS layer. This allows for scaling the workflow to larger projects where your system resources may not allow for processing all Cycles in a single run, or for times where you may be processing data blocks as they’re acquired and adding more over time.
• When not using Strip Adjustment or Strip Align , in the TOC, select the desired LAS Layers to be merged or copied, and use the TOC - right-click menu -> Merge LAS Layers command or Copy LAS Layers command to open the Merge LAS Layers dialog or Copy LAS Layers dialog in order to merge or copy the individual Cycle/Flight LAS layers into a single combined LAS layer before smoothing or ground classification.
• For more selective processing you might select individual LAS file(s) in the LAS Files tab and use the right-click -> Move Selected File(s) to Layer command to open the Move LAS Files to Layer dialog. This command allows you to move one or more LAS files from one LAS Layer to another. You can also create a new destination LAS Layer with this command.
• For 3DIS® or DJI L1/L2, if running the Smoothing Point Cloud PCT after Strip Adjustment or Strip Align or after merging/copying LAS Layers, select the Output Structure as “Tiled Files” to create suitable sized LAS files for downstream processing in LP360 such as ground classification, etc., when using QVR pyramids. This is not necessary when using LPLAS.
• For 3DIS® or DJI L1/L2, if not running the Smoothing Point Cloud PCT, then after merging/copying LAS Layers, use the Merge Point Cloud PCT to create suitable sized LAS files for downstream processing in LP360 such as ground classification, etc. Files should be no larger than 256MB on disk for optimal performance when using QVR pyramids. This is not necessary when using LPLAS.
• If you wish to subset RetainedPhotos layer(s), select the desired layer(s) in the TOC and use the right-click Merge Feature Layers and/or Copy Feature Layer command, as applicable, to create an editable copy that is easy to delete and re-create if needed. When running Agisoft Ortho Mapping or Ortho Mapping tools for multiple Cycle/Flight RetainedPhotos layers, it is not necessary to merge or copy them first, just select the desired layers in the Agisoft Ortho Mapping or Ortho Mapping dialogs.
• If not running the fully integrated Agisoft Ortho Mapping or Ortho Mapping tools, create a single photo package for all Cycle/Flight RetainedPhotos layers by always selecting the same output folder for the Export Photo Package  tool as you toggle between each applicable Cycle/Flight combination.
  • • If your project area is very large and has a lot of photos, then you may need to section it into overlapping sub areas depending on the capabilities of your photogrammetric software and the capabilities of your hardware.

• After running Agisoft Ortho Mapping or Ortho Mapping  tools or manually processing the photo package in another photogrammetric package:
  • • Add the orthomosaic raster to your project. For Agisoft Ortho Mapping or Ortho Mapping , this is done as part of the Complete Job step in Job Manager , along with updating the image EXIF tags with the bundle block adjustment positions and angles to improve the image drives for Image Explorer .
    • Use the Reproject Raster PCT to create a new raster clipped to the project deliverable boundary by selecting the polygon layer as the Tool Geometry and the orthomosaic as the Input Raster Layer. Deselect the Convert CRS to maintain the current CRS on the orthomosaic.
    • Running the Reproject Raster PCT on small rasters can create the output as a regular TIFF that can be added to Autodesk’s Civil3D, an example of a program which cannot read the BigTIFF file format typically generated by Metashape and other photogrammetric processing packages. Rasters resulting in a file >~4GB cannot be written in the TIFF format so be sure to select the Create BigTIFF File option when running the Reproject Raster PCT, or use an index, which can be generated using the Grid Generator PCT, to cut a single large raster into smaller rasters to fit the TIFF format.