Coordinate System
A coordinate system is a reference system used to represent the locations of project data within a common coordinate framework. A coordinate system can be projected (X, Y), geographic (latitude-longitude), or geocentric (X, Y, Z). Each coordinate system is associated with its Well-Known Text (WKT) description, a simple structured, text-based format for spatial reference system information that is easy to store and share between systems (See https://www.ogc.org/standard/wkt-crs/). A coordinate system can optionally include a vertical datum that defines the origin for height values.
When you add input data to a project, PhotoMesh reprojects the various inputs to the AT’s project coordinate system and eventually to the output’s coordinate system. The inputs and other project information (e.g., calculated photos and output previews) are also reprojected to the 3D Window’s Lat-Long WGS84 coordinate system (with vertical datum if provided). If an input source does not include coordinate system information or PhotoMesh is unable to read this information, you must supply it so that PhotoMesh can reproject the source. Usually, the data supplier provides the information about the coordinate system used for each source.
The Coordinate System dialog is used to define the coordinate system for all project data.
When data is in Lat-Long WGS84 or ECEF coordinate system and no other coordinate system was used for photos and ground control points, etc., the default system used is the Universal Transverse Mercator (UTM) grid system with the UTM zone based on where the center of the data falls.
To set the coordinate system:
1. Open the Coordinate System dialog.
Coordinate System Dialog
2. Enter the coordinate system information using one of the following methods:
§ Click History and select one of the recently used coordinate systems. The last 20 coordinate systems used are saved in the History for future use.
§ In the Search field, type the EPSG code or a phrase from the Coordinate system Description, as indicated by the supplier, and click Search. Then select the required result from the search results displayed directly below.
§ In the Well-Known Text section, type the WKT. The Well-Known Text representation of spatial reference systems, regulated by the Open Geospatial Consortium (OGC), provides a standard textual representation for coordinate system information. You can edit an existing WKT.
Note: A custom coordinate system is listed with all the other coordinate systems, with an asterisk in the Custom column.
3. If your coordinate system includes vertical datum, click Set and select a vertical datum from a list of supported datums.
Note: If the WKT of your coordinate system references a particular grid shift file that was not bundled with the PhotoMesh installation, you can add the file by downloading it and placing it in the correct directory. See "Adding Grid Shift Files" in this chapter for information.
4. Click OK.
The following advanced coordinate system capabilities are available: