Composite Surveys: Frequently Asked Questions (FAQ)


Who can create Composite Surveys?

Users with Process level permissions to a site can create composite surveys. 

What can I merge?

All surveys, including Propeller processed, pre-processed, and point cloud uploads.

Please note: We will merge terrains generated from point cloud uploads. However, point cloud tiles can't be merged.

Can I create a Composite Survey on top of another survey?

Yes. Some sites are too large to fly frequently, and you might only be interested in one area of the site. In that case, you can fly a smaller area and merge it on top of your entire site survey. The newest survey would take priority over the old (it would be the topmost layer).

Can I download my whole composite?

Not yet. We're working on a feature that allows you to download the GeoTIFF from Files in the OUTPUTS tab. This will be helpful for uploading files into dedicated Geographic Information Software (GIS) like QGIS, ArcGIS, or Global Mapper. 

Exporting any size measurement (such as one covering the whole composite) in some formats that suit your needs is possible.

OutputsTab_SurveyFiles.png

What can I download / export from my composite?

Supported exports

  • Outlines in DXF and KML
  • Surface mesh in DXF and TTM
  • Contours in DXF

Not supported exports

  • All other exports
    Including pre-made exports from “Files” modal, and dynamic exports.

Will composite datasets work with BYOD data?

Yes.

The primary difference is that we assume that pre-processed data has been trimmed appropriately and, therefore, includes the entire survey. The survey trim boundary can be adjusted manually.

Can I edit my composite terrain?

Not directly.

You can edit the terrains of any partial survey, and these changes will flow through to any composite survey that references this partial survey once you refresh your browser.

How can I edit the boundaries around/between partial surveys of my composite survey?

1. Edit and save the relevant boundary measurement(s) in the "Composite Trim Boundaries" measurements folder.

MeasureTab_Composite_EditShape.png

2. Find your composites in the dataset drop-down menu and click the settings button to modify the composite.

CompositeSurveys_MergeSettings.png

3. Leaving everything as it is, follow the prompts to re-create the composite survey.

That's it! Your composite should now respect the boundaries you've set.

Best practices for capturing surveys to be used in composites

Overlap between surveys

3-5 passes from each partial survey overlapping is recommended to ensure you have more to work with if the boundary between them isn’t ideal for your site conditions.

It’s possible to merge surveys with little or even no overlap. However, data becomes less accurate towards the edges and is generally less useful without overlap.

Flight settings

With enough overlap between surveys, the right equipment, best practices, no big elevation changes on the boundaries, etc. your composite surveys will work perfectly.

This is always relevant when capturing data that you want to use with any other data. That said, accuracy issues become much more obvious when using composite surveys.

Ground control point (GCP) distribution

Again, following the best practices for capturing globally accurate surveys will get great results.

If you're not using Propeller PPK, getting your GCPs to surround the area that you want to be accurate and merge nicely with the survey next to it is even more important.

Expected accuracy and look

This entirely depends on how well each survey merged was captured.

Flying in similar conditions with best practices will give no significant ( 3cm | 1/10') change between surveys.

Flying in differing conditions (different time of day, levels of cloud cover etc.) may result in the surveys looking different in color.

Flying any of the surveys to be merged with poor practices, or the wrong equipment will likely cause big step changes in elevation on the boundaries.

 

What happens if I archive a survey used to create a composite?

This should be avoided.

Archiving any source datasets will remove them from the composite after ~30 days.

When I zoom in on my composite survey, why can some parts look blocky?

Each partial survey has a maximum zoom level determined by the ground sample distance (GSD). If all of the surveys in a site were captured using a similar drone/camera flown at around the same altitude, it would result in relatively similar terrain resolutions and, hence, similar maximum zoom levels.
However, due to different site conditions and other factors, it’s possible to have surveys on the same site to have different maximum zoom levels.
To ensure that the highest terrain resolution is available when generating a composite survey with different maximum zoom levels, partial surveys with relatively lower maximum zoom levels will be upsampled to the maximum zoom level of the most detailed partial survey.


I still can't do it!

We wrote these articles to equip you with everything you need to get the job done on your own, but we understand that sometimes this isn't sufficient.

If you're stuck, you can connect with our support team by clicking the support button on the top right corner of your user portal.

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