Datamine Discover KB - Projections

How do I change a projection for a layer which is misregistered (without changing coordinates)?

kbadmin — Thu, 22 Feb 2024 03:38:56 GMT

Occurrence

Vector objects such as Lines, Polylines or Polygons have been digitised into the incorrect projection. In this case, reprojection does not work, as the object coordinates will change (move). For
example the vector object may have been created in the incorrect UTM Zone, or the wrong projection was selected during import and registration of the file.

How can this be modified without recreating the objects/registration?

Solution

For vector data you can use this tool that you can install by going to Home>MapInfo Marketplace, and find CoordsysChanger and install it.

http://mapinfomarketplace.precisely.com/product/4d68d42c-7d5a-40c8-ab37-56c005176049

For rasters or surface grid images, simply use Table>Raster>Modify Image Registration, and select a new Projection, or edit control points. Note that editing control points may cause errors, which ought to be fixed through rectification.

For points, you can firstly save the coordinates using DISCOVER>Projections>Updates Coordinates. Then simply delete the map, using Table>Maintenance>Table Structure and un-ticking Table is Mappable, and then re-create the points.

How do I reproject my data?

Josh Knight — Fri, 19 Nov 2021 07:21:42 GMT

MapInfo and Discover provides a number of different Reprojection Utilities, depending on the type of data to be transformed. Each of these tools will create a copy of the data in the specified output projection, typically with a default _reproject suffix added to the input file name. These tools are invaluable (for example) for ensuring all datasets are in the same Coordinate Reference System (projection).

Note: After reprojecting when you open in back in the map window, it will appear in exact same location. This is due to Mapinfo being a GIS system that reprojects on the fly. It will only appear in a different location when opened in a non-GIS program.

Vector data (i.e. points/polylines/polygons)

This is shown in the layer control with an icon -

There a numerous ways to reproject these -

1. Standard MapInfo way is to go to Home>Save>Save Copy As. Then on the save dialog, click the projection button and choose the new projection.

2. Use the Discover>Reproject>Reproject Coordinates. This uses the Discover projection engine with explicit NTv2 support. (note this doesn't support NativeX tab files).

3. Use the DISCOVER > Reproject > Multi-Table Reproject tool. This allows the current projections of multiple vector tables to be displayed and reprojected, either as new tables, or overwriting the existing tables.

Note with all of these methods only change the spatial vector data in the map. They do not update any coordinates in the browser table for say points. There ...

What are the [EPSG:XXXX] or "\pXXXX" codes at the end of a projection name?

kbadmin — Wed, 01 Apr 2020 04:40:06 GMT

The "\pXXXX" numeric codes that appear at the end of projection names in some projection selection
dialogs are the corresponding EPSG code for the projection.

These are used by GIS software packages to when converting files to different GIS formats, to define a common standard coordinate system different software can understand.

For example, when MapInfo exports a geopackage file or a ArcGIS Shape PRJ file. The MapInfo coordinate system is converted based on its EPSG code.

Custom or local affine coordinate systems are no supported by the EPSG database. Archaic projection systems also do not usually exist in the EPSG database.

How do I add a custom projection to MapInfo and Discover

kbadmin — Tue, 27 Aug 2019 00:10:24 GMT

Occurrence

I've added a custom projection line to my MAPINFOW.PRJ but it does not appear in the select projection dialog box's list.

Solution

If the projection is not appearing in MapInfo Pro, it will need to added to the default MAPINFOW.PRJ file located in -

C:\Program Files\MapInfo\Professional (64-bit)

C:\Program Files (x86)\MapInfo\Professional (32-bit)

Note that these are read only locations, so you will need to copy the file to your desktop, edit it, and then copy back to overwrite with the changes.

If it is still not listed check the format is exactly correct by copying the exact formatting -

"--- Custom name ---"
"Projection name", x, x, x

You should also use DISCOVER>Projection Editor to create the custom coordinate system string.

If using Discover 2017 Update version or later, you only need to update the 1 PRJ file. Other PRJ files are kept in sync. Also there is a new Projection Editor tool to add custom projections, and update both files.

If you wish to share the same PRJ file on a network drive for all users, this can be set using the MapInfo Workgroup directory setting in PRO>Options>Directories.

On older versions, Discover's reprojection tools and Discover3D use a separate projection file (to MapInfo Pro) which you will need to copy and paste the custom projection lines into It has the identical format as the Mapinfow.prj file..
It is located at-

C:\Users\USERNAME\AppData\Roaming\Encom\Common\Projections\Encom.prj

How do I determine the projection of a map window or table?

Josh Knight — Wed, 11 Apr 2018 00:22:38 GMT

In MapInfo 64-bit, the projection is displayed in the Status Bar at the bottom of the Mapinfo window.

Alternatively, Right click in the mapper window and select the Projection Info from the pop-up menu. The first tab while show the Map's projection, and other tables will display each layer's projection.

To change a Map windows projection, you will need to navigate to MAP>Map Options dialog, and click projection.

How do I create a custom affine projection or local mine/sample grid to use in MapInfo?

kbadmin — Wed, 26 Oct 2016 04:17:32 GMT

Occurrence

I need to view both my local mine grid data and real earth data in the one mapper window. Traditionally many people use a simple Non-Earth (metres) coordinate system to display local mine gridded data, or data from a sampling grid in a project area.

Creating a custom affine projection will allow the local mine data to be directly compatible with any real world coordinate system.

Solution

The control point table for a custom affine projection transformation must contain four columns which read from left to right as UTM_Easting, UTM_Northing, Local_Easting and Local_Northing. The naming convention
of the column headings is not important, but the order of the columns is critical. An example of a control point table can be seen below.

To generate a custom projection system for the non-earth coordinates -

1. Open the table to transform into MapInfo. The transformation target table must be mappable and in a standard projection, e.g. UTM or MGA. If no data is available, you may also use the Control Point table for the transformation target table, by simply Creating Points for the UTM (MGA) coordinates.

2. In the DISCOVER>Projections>Custom Transform (or Discover>Data Utilities>Transform Coordinates) dialog, select the table to transform from the Transformation Target Table list.

3. Choose ...

What is the Popular Visualisation projection?

Josh Knight — Tue, 02 Aug 2011 06:53:02 GMT

From :

http://georepository.com/crs_3785/Popular-Visualisation-CRS-Mercator.html

"Popular Visualisation CRS / Mercator is a projected CRS last revised on 03/14/2008 and is suitable for use in World between 85°S and 85°N. Popular Visualisation CRS / Mercator uses the Popular Visualisation CRS geographic 2D CRS as its base CRS and the Popular Visualisation Mercator (Mercator (1SP) (Spherical)) as its projection. Popular Visualisation CRS / Mercator is a CRS for Certain Web mapping and visualisation applications. It was defined by information from Microsoft.. Uses spherical development. Relative to an ellipsoidal development errors of up to 800 metres in position and 0.7% in scale may arise. Some applications call this WGS 84. It is not a recognised geodetic system: see WGS 84 / World Mercator (CRS code 3395)"