A coordinate reference system (CRS) defines the location of a point on a plane or a sphere. It provides the X, Y, and Z locations for all points in space, and allows you to consistently determine where you are on Earth.

On construction sites, operations are often defined in a specific local or custom coordinate reference system (CRS) to make measurements more accurately and to comply with standards set for the sites.

How are coordinate reference systems used in Sitemark?

Sitemark needs to know what coordinate reference system (CRS) you are using, so that your location data is usable and readable. Sitemark supports custom coordinate reference systems based on EPSG codes. By default, all location data on the Sitemark platform is in WGS84 (EPSG 4326).

If the CRS of one operation does not match the CRS of another operation or DXF overlay, you will not be able to combine them in one view in the Sitemark platform. There will be geospatial shifts and geographic discrepancies if the CRS doesn't match.

You can always change a CRS for the site if you need to make it match a DXF design overlay or other geospatial data from the site.

There are multiple places in the Sitemark platform, where you will have to set or select the coordinate reference system:

When creating a site

When you create a new site, you can provide a default coordinate reference system. This will be used as the default coordinate system when creating new operations or uploading DXF design overlays on your site. You can still update this later, or override it at the moment of creating operations or uploading overlays.

When creating an operation

When you create a new operation, in the second step you will be asked to select the coordinate system which will be used during processing. This is by default set to the CRS that you selected as the default for your site. In case you are using ground control points, this coordinate system needs to match the CRS of the ground control points. The downloads of raw data will also be available in this CRS.

When creating a new operation, you can override the CRS to be different from the site CRS. In such case you will get a warning since future data might not align with existing data, or DXF design overlays.

When tagging ground control points

When tagging ground control points, you can still override the CRS of the operation. Please keep in mind that the downloads of raw data will also be available in this CRS.

For more information on how to tag ground control points, follow this guide.

When uploading DXF design overlays

If you are uploading DXF design files, for example to use as a base surface for volume measurements, the CRS needs to match with the CRS of the operation in order to avoid geospatial shifts and geographic discrepancies.

You can still override the CRS of the DXF overlay here, but you will receive the following warning.

When downloading operation outputs

When operations have completed processing, you are able to download operation output data such as point clouds, or measurements. These downloads will be generated in a specific coordinate reference system. For more information, please read this guide.

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