DesignSeries.pngSpecifying document georeferencing

Command

Path

Georeferencing

File > Document Settings

The goal of working with a georeferenced drawing in Vectorworks is to align the drawing’s internal origin, and therefore its geometry, with a specific location on Earth. Georeferencing options are complex; what works for architectural workflows may not be suitable for a planning workflow. Additionally, different regions of the Earth have different geographical requirements. Since the earth is not a perfect sphere, it is not a straightforward process to correlate the Earth’s three-dimensional surface with a two-dimensional map. Coordinate systems use mathematical formulas to translate the shape of the earth onto a 2D page. Because the translation loses data, different coordinate systems are preferable for different regions of the globe.

A proper coordinate system has a big impact on distance measurements. A distance in the drawing and the same distance on the map will match, more or less, depending on the selected coordinate system. The closer the match to the region being worked upon, the closer and more accurate the measurements and dimensions are.

When georeferencing is enabled, each design layer saves information that describes the mapping of that layer’s Cartesian coordinate system onto a geographical coordinate system of latitude and longitude or easting and northing. The origin offset determines how the geographical coordinate system relates to the internal origin (the center of the drawing in the Vectorworks file); this offset can be adjusted at the document level or at the layer level.

The Georeferencing parameters set up the document’s georeferencing. Normally, all or most design layers have the same georeferencing information as that of the document; layers without georeferencing enabled automatically assume the document georeferencing settings. A georeferenced layer moves with changing geolocation (essentially, remaining on the globe), while a non-georeferenced layer always remains around the internal origin. After the document georeferencing is set, you can enable and customize a layer’s individual georeferencing settings differently, but this is rarely needed.

When importing a shapefile, the document georeferencing can be automatically set to match the coordinate system of the imported file.

To set georeferencing for the document:

Select the command.

The Document Georeferencing dialog box opens.

Click to show/hide the parameters.Click to show/hide the parameters.

Parameter

Description

Adjust origin and orientation of georeferenced data to match document coordinates

These options affect the way the Vectorworks drawing (internal origin) relates to the geographical location. You can offset the location of the georeferenced data so that it matches the way that the coordinate system relates to the drawing’s internal origin.

Normally, these options should be enabled and set to a location close to the site. This ensures that your drawing work on the site is within the double-precision limits required for accurate mathematical calculations and operations in Vectorworks.

Latitude/Longitude

Specifies the latitude and longitude at the document origin (0,0); enter decimal degrees, or degrees/minutes/seconds (for example, 39.18, 39° 10’ 32”, or 39d 10m 32s) preceded by a minus (-) sign when appropriate

Angle to True North

Specifies which direction is north from the document origin; use an azimuth degree measurement (0° is along the Y axis, 90° is along the positive X axis)

Select a coordinate system

Select one of the Coordinate systems based on the drawing’s geographic location and the extents of the drawing; additional parameters that are required to map to the selected coordinate system display in the area below

Use WGS84/Pseudo-Mercator for worldwide use

This global coordinate system is good for general purposes, but because it displays the entire globe, distortion can reduce accuracy when matching the Vectorworks distances and the map distances. If possible, select a more regionally-specific coordinate system.

Use an EPSG code or CRS name

Uses the International Association of Oil and Gas Producer's EPSG Geodetic Parameter Dataset code or Coordinate Reference System (CRS) name to specify the coordinate system. Click EPSG/CRS Lookup to select the desired reference system from the EPSG/CRS Lookup dialog box. The selected system displays in the Document Georeferencing dialog box.

Enter text in the Filter field to filter the list.

Use a projection ( .prj,  .proj4,  .xml) file on your computer

If you have a specific projection file for the georeferencing coordinate system, click Browse to select it

Use a common coordinate system or enter Well Known Text (WKT)

Select one of the Vectorworks default Coordinate systems that is supported by GDAL (Geospatial Data Abstraction Library), or select to use the WKT markup language. From the Coordinate System list, enter one or more terms in the search box to filter the list.

Depending upon the selection, additional parameters display in the area below.

Text

Displays a description of the coordinate system data.

You can edit the coordinate system text and save it for future use. Click Save or Delete to add/remove a custom item in the Coordinate System list; specify a unique CRS Name when saving if you do not want to replace the existing data.

Click EPSG/CRS Lookup to select the desired reference system from the EPSG/CRS Lookup dialog box.

Ellipsoid

Select the appropriate reference ellipsoid used to create the coordinate system

UTM Grid Zone/Hemisphere

For the Universal Transverse Mercator (UTM) coordinate system, select the UTM grid zone and UTM hemisphere that apply to this drawing

State/Zone

For a State Plane Coordinate System (NAD83 or NAD27), select the state and zone that apply to this drawing

Center Latitude/Longitude

Specify the latitude and longitude of the center of the selected coordinate system

Scale

For the Transverse Mercator coordinate system, specify the scale factor along the central longitude; for the Stereographic coordinate system, specify the scale factor at the central point

Standard Parallel 1/2

For the Lambert Conformal Conic coordinate system, enter the two standard parallels to use for the coordinate system

Transformation mode

Select the appropriate option for transforming the geometry of objects on the layer if the layer’s coordinate system type changes:

Do not transform this layer’s geometry: Layer objects will not be transformed when the layer’s coordinate system is changed.

Transform all geometry individually: Best for projecting geographic data, such as municipal boundaries, roads, rivers, and locations on a map.

This option ensures that the drawing items match the georeferencing of the layer’s coordinate system. If you have made any manual adjustments to the Latitude/Longitude offset or the North angle, select this option.

Move and rotate all geometry as a group: Best for projecting non-geographic drawing objects, such as architectural plans.

Transform images to match layer’s coordinate system

For imported georeferenced images, ensures that the image pixels are at the correct latitude and longitude to match the layer’s coordinate system; when selected, image objects are also transformed if the Transformation mode is changed.

Reset

Discards any edits made and returns all fields to their former values

Enable georeferencing for each design layer that requires it, as described in Specifying design layer georeferencing.

Advanced import options: GIS pane

Importing Shapefiles

GIS and georeferencing

 

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