Spatial Manager™ for GstarCAD - FAQs: Transform drawings Coordinate System ("Professional" edition only)

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Introduction

• Objective of this section
  • To learn how to define the Transformation of a drawing Coordinate System

• Topics in this section
  • Coordinate Transformation
  • Entities selection
  • Transformation parameters

Can I transform the entities geometry by defining a Transformation of the drawing Coordinate System?

You can transform the Coordinate System (CRS) of a whole drawing or a set of selected entities by executing the 'SPMTRANSFORMCRS' command of Spatial Manager™ for GstarCAD, which automatically creates a new drawing including geometrically regenerated entities from the current drawing according to the chosen transformation between two CRSs. At the end of the transformation process, the newly generated drawing will also be automatically opened. This functionality has been designed to execute this Transformation in a direct and highly automated way, regardless of whether other application functions can perform geometric transformation operations between Coordinate Systems of entities or Background Map images, if these are necessary in Import, Export, Background Maps, etc. processes

Transform drawing Coordinate System functionality (Original and transformed drawings overlapped in order to show the transformation)

• Transformation selection
  • Select all entities: all entities in the drawing will be transformed
  • Only selected entities: only a selection of entities will be transformed. You can select the entities before executing the Trasform CRS function or by using the Selecting button in this window
  • Select entities in a layer: only the entities included in a GstarCAD Layer will be transformed. You can select this layer using the drop-down list in this window
    • Note: When choosing the option to transform all entities in the drawing, those entities that are in locked, off or frozen layers will not be included. If the entities are selected by any means before transforming and the option to transform the selected entities is chosen, they will be transformed even if they are in locked, off or frozen layers
• Entities report: the application shows here the total number of the entities which will be transform and any warnings prior to the transformation process, such as the total number of unsupported entities which will not be transformed or others

will When you are Importing Features as GstarCAD Entities using Spatial Manager™ for GstarCAD, you will see that you can choose a Transformation of coordinates from the source Features to the Entities in the drawing, in the "Import" wizard. This means that the application will calculate a geometric transformation between the source and the target data, which will depend on the chosen CRS for the source (incoming Features) and for the target (imported GstarCAD Entities) data. You can choose the appropriate CRSs by clicking on "CRS catalog...", in the CRS dropdown list for the source or for the target data. In the CRS table you can:

• Filter the CRSs by type (Geocentric, Projected, etc.)
• Choose a CRS by clicking on its row in the table
• Search CRSs by typing the search criteria in the "Search" box. You can type here as many words as you like separated by blanks. The application will find all the rows including all these words in any column of the table

After choosing a pair of valid CRS for a Transformation, you can choose the geographic Area to apply it to (the application will choose by default the most common Area for this Transformation)

If the application "knows", "guesses" or "can assume" the CRS of the source and/or the target (drawing) data, it will be chosen by default. You will be able to modify this choice except in cases where only one CRS is valid; for example, for a KML or a KMZ file the only valid choice is the CRS "WGS84 (SRID 4326)", because these types of file are always defined using this CRS

You can assign a CRS to the drawing, or modify it, using the command 'SPMSETCRS'. By executing this command, you will access the CRS Catalog of the application, described in the previous lines. In this case the Type "Projected" will be selected by default because is the most common choice

• When importing a table defined using a known CRS into a drawing without an assigned CRS, the CRS of the table is automatically assigned to the drawing
• If you change the target CRS by choosing any CRS other than the drawing CRS, you will get a warning from the application but you can continue and perform the Transformation of coordinates if you want to

• Notes:
  • To unassign (undefine) the Coordinate System of the drawing, choose "Undefined CRS" (EPSG 0)
  • As you will see, the CRS dropdown lists will include more and more CRSs as they have been previously chosen in other Transformation operations, so that you can choose your "last-used" CRSs directly from the dropdown list without having to access the CRS Catalog all the time. In addition, the CRS Catalog window shown when you execute 'SPMSETCRS' to assign a CRS to the drawing, or modify it, also includes a list of the "last-used" CRSs (if any) in the upper zone
  • If the incoming data is defined using the CRS "WGS84 (SRID 4326)" and the drawing has not assigned any CRS, the transformation to the CRS "WGS 84 / Pseudo-Mercator (SRID 3857)" is selected by default to get a projected map instead of a flat representation of geodesic coordinates
  • Coordinate Systems and Transformation details
  • Coordinate Systems objects available in the current version

Related links

• Go to FAQS