Creating virtual mosaics from drone data involves clipping together a collection of separate DSMs and orthophotos to form a seamless, comprehensive terrain model of a particular area. This kind of work applies to long stretches of road or large fields that are flown in sections, which are often flown on different days or weeks and loaded into Virtual Surveyor separately. You can clip the edges of the drone data and make them flush with each other so that all the DSMs and orthophotos display as a single terrain, but still be capable of managing portions of the project site in separate sections. 


We'll show you what options you have for creating a virtual mosaic, how to set the order of your Terrain States, how to clip overlapping terrains for cleaner edges and be flush against each another, and how to export your elevation and image terrains as a .tif file.


Tip: If you want to merge your drone data into a single elevation terrain and orthophoto instead of managing multiple sections separately as a virtual mosaic, you can read about how to do that in our Handling Data Tiles article. The process for merging data tiles into a single elevation terrain and orthophoto is the same for merging different sections of DSMs and orthophotos within a project site.


Overview


Options for Creating Virtual Mosaics

To create Virtual Mosaics, Virtual Surveyor has the following tools available:

  • Set the layer order of the different DSMs and Orthophotos (Elevation and Image Terrains). 
    • This functionality allows you to control exactly what DSM/Orthophoto is on top of the other when they overlap.
  • Create clean seams between the different blocks with the clipping tool.
  • We recommend creating your survey, contours, or TIN on the virtual mosaic and exporting the data to a CAD compatible file format (.dxf, .xml, ...). 
  • As another option, you can export your mosaic to one combined GeoTIFF or JPEG2000 file.


Note! You can create virtual mosaics in Virtual Surveyor up to a maximum of 250 km (155 miles) in any direction.



Set the Order of Your Terrain States

  • You can change the order of a Terrain State with Move Up or Move Down functions.
  • The Move Up or Move Down buttons appear when you have selected at least one Image (Orthophoto) or Elevation Terrain (DSM).
  • Click Move Up or Move Down to change the order of the terrain compared to the other terrains.
    Image showing an overlap of terrains on different Terrain States between two separate drone flights.Image showing the Terrain States after moving one on top of the other.








Clip the Terrain to the Boundary

  • The Clip button appears in the contextual TOOLS tab when you have the Orthomosaic/DSM and a Boundary selected.
  • Once you have both the boundary and terrain selected, click Clip to trim the terrain to the boundary limits.

    Two terrain states are clipped together within a boundary line.


Export Your Terrain

  • The Export Terrain button is available in the EXPORT tab.
  • Create a boundary for the total area you want to export.
  • Click Export Elevation to .tif or Export Image to .tif to export the orthomosaic as a terrain file.

    Final image of a virtual mosaic being exported as a single elevation terrain file and image terrain file.