> For the complete documentation index, see [llms.txt](https://docs.jakarto.com/guide-data-downloader/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://docs.jakarto.com/guide-data-downloader/en/data-selection/coordinate-system-choice.md).

# Coordinate System Choice

By default, downloads use the source CRS (typically an MTM CSRS horizontal CRS and CGVD2013 vertical datum).

You can change the horizontal and vertical CRS independently. The dropdown lists only show CRS that are valid for all currently selected files (intersection of allowed transformations).

Notes:

* Changing either horizontal or vertical CRS triggers on-the-fly reprojection.
* Any reprojection leads to a LAS output; without reprojection and when LAZ is preferred, the tool delivers the native COPC (.laz).


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