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Handling GeoJSON Files with Unspecified Projected Coordinate Systems

In the latest GeoJSON specification (2016), the coordinate reference system for all coordinates is a geographic coordinate reference system—using the World Geodetic System 1984 (WGS 84) datum—with longitude and latitude units of decimal degrees. The previous specification (2008) allowed for the use of alternative coordinates systems, but this was removed because of interoperability issues.

MAPublisher still recognizes GeoJSON files with a specified coordinate system even though it is no longer officially supported. However, if no coordinate system is specified, MAPublisher will assume the coordinates are in WGS 84. Occasionally, this may cause a problem of improperly formatted files that contain projected coordinates but have no specified coordinate system. In this case, users will need to either choose a coordinate system during import or modify the GeoJSON file by adding a coordinate reference system (CRS) object manually.

Selecting a Coordinate System on Import

To change the coordinate system using the Import dialog box, click Advanced and select the WGS 84 link under Coordinate System. Ignore the warning about changing the coordinate system by clicking “Replace coordinate system”. Select the correct projected coordinate system from the list.

 

Modifying the GeoJSON File Manually

Coordinate reference systems can be specified in a GeoJSON file using a CRS object. You can view the contents of any GeoJSON file by opening it in a text editor such as Notepad. Copy and paste the text below after the line: “type”: “FeatureCollection”, (usually on line 2). Change the EPSG number to the correct CRS for your dataset. See Spatialreference.org to lookup an EPSG code.

"crs":
{
   "type" : "name",
   "properties" :
   {
      "name" : "EPSG:[EPSG Code]"
   }
},

Example:

The GeoJSON file can now be read properly by MAPublisher and can be imported as normal.

Cleanup Lines With MAPublisher Trim and Extend Tools

The latest release of MAPublisher includes the ability to trim and extend objects to a crossing or intersecting path. Extending a path lengthens it to meet the edge of a crossing object and trimming a path cuts the portion that extends past the edge of an intersecting path. Trim and extend tools are commonly used in CAD software and will greatly improve the ability to produce accurate and precise data in MAPublisher and clean-up imported data.

Location of the Trim and Extend tools on the Adobe Illustrator Tools panel. Click and hold the tool button to switch between MAP Trim Tool and MAP Extend Tool.

The MAP Trim Tool and MAP Extend Tools are located on the Adobe Illustrator Tools panel. Click and hold the MAP Trim or Map Extend tool button icon to switch between them. To use the tools, select the crossing or intersecting path and click the object to extend or trim. The diagram below illustrates the basic process.

Visualization of the trim and extend processes

There are many possible applications for these tools in digitizing and cleaning map data. In a hypothetical example illustrated below, we trim all the roads that extend past the edge of a border, and extend the imported roads (in bold) to meet the existing roads.

Examples of uses for the trim and extend tools. Extending imported roads to match existing roads and trimming lines that fall outside of a map border
Lines trimmed and extended!

Use MAPublisher to Import Layers from ArcGIS Online Directly Into Adobe Illustrator

With the latest release of MAPublisher 9.9, it’s now possible to easily import layers directly from an ArcGIS Online account or an ArcGIS web service. This will allow you to use shared data layers within your ArcGIS Online organizational account and connect to publicly available map servers from various online sources.

ArcGIS Online is a collaborative web GIS that allows you to store and share GIS data using Esri’s secure cloud. Before, you may have had to download layers as shapefiles to your local machine and then import them into Adobe Illustrator using MAPublisher. Now, MAPublisher has a much improved workflow to get ArcGIS Online layers into Adobe Illustrator will full georeferencing, all map features, and attributes.

Currently, the types of datasets allowed are Feature Layers, Map Image Layers and Tile Layers. To load a layer, use MAPublisher Import as you would with any data type and select ArcGIS Online from the Format drop-down menu. Click the login link to enter your ArcGIS Online credentials to access your organization’s web portal.

Import ArcGIS Online dialog box
ArcGIS Online user portal

Feature Layers contain vector data that will import as artwork into Adobe Illustrator. Optionally, you can extract specific features using standard SQL queries. Map Image Layers and Tile Layers are raster data layers that can be added by selecting the geographic extents.

Import Image Map Layer

In addition to using your own organization’s data, you can connect to publicly available data from a wide variety of organizations by connecting to an ArcGIS Web Service. To connect to a web service, use MAPublisher Import and select ArcGIS Web Service from the Format drop-down menu. Click to select the dataset and enter the URL for the service. This is a great option when searching for data from open data portals created by government agencies.

Import ArcGIS Web Service
Valid ArcGIS Web Service

Accessing Esri’s online services through MAPublisher provides a great opportunity to use shared data within your organization and access a wide variety of publicly available data. We’re sure you’ll find it very useful for finding data to make great maps.

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