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Aligning data with different coordinate systems in MAPublisher

When first creating a map, very often you will find yourself having to align GIS data, especially if it is found or supplied by various sources. You might find that the coordinate systems assigned to each of the datasets might be different. This can prove challenging for many cartographers and GIS users. However, with MAPublisher, you can transform and align your datasets to one coordinate system very easily using the MAP Views panel.

Imported maps have different coordinate systems

For example, we have five layers with three different coordinate systems. After importing them into MAPublisher, the result is three different MAP Views. The MAP Area layer (Province) is in a Lambert conformal conic projection. The MAP Line Layer (river) and MAP Area layer (lake) are in a Robinson projection. Lastly, the MAP Point layer (cities) and MAP Line layer (roads) are in a geodetic coordinate system WGS84.

5 MAP Layers with 3 different MAPViews

Let’s decide that the map we are creating here will have a Lambert conformal conic projection (the MAP View with the province area layer). Now, simply select the two layers in the Robinson MAP View, then drag them to the “Lambert Conf. Conic – 1: 30,000,000” MAP View.

MAPublisher trick: Drag and Drop Transformation

The rivers and lakes layers are now transformed and aligned to the province boundary layer.

Two map layers are transformed and aligned properly.

We will do the same for the cities and roads layers in the “WGS84” MAP View. Select the two map layers (cities and roads layers) then drag them to the “Lambert Conf. Conic – 1: 30,000,000” MAP View.

MAPublisher trick: Drag and Drop transformation for two map layers

The cities and roads layers are projected on-the-fly. Now every layer is transformed to a Lambert conformal conic projection and aligned appropriately.

Every map layer is transformed and aligned properly


Related topics

University of Montana Student Map Submissions

MAPublisher is popular with educators and students because, in no time at all, new users can begin to create great looking maps. Working seamlessly with the Adobe Illustrator environment, users can spend more time on map details and less time fighting with complicated importers and data format conversions.

Avenza Systems Inc. recently received student work submitted by the Univeristy of Montana’s Digital Design course. These maps show some excellent terrain shading, good colour choices, and a knack for making complex cartographic detail legible.

We wish to thank the students for generously allowing us to distribute their work, and we wish them luck in their upcoming mapping endeavours.

Click the maps to load high-resolution versions.

Buffalo Bill State Park Wyoming

by: Nathan TaylorBuffalo Bill smaller


Crown of the Continent

by: Nathan BaldingCrown of the Continent smaller


Lolo Pass Recreational Trails

by: Hal Bobbitt Lolo Pass Recreational Trails

Georeferencing an Image in Adobe Photoshop with Geographic Imager

Today's topic: making an image georeferenced

As of Geographic Imager 5.0, there’s an updated workflow for georeferencing images. Learn more about Georeferencing and work through the tutorial.


Nowadays, it’s common to find great orthophotos and satellite imagery on the Web. However, after downloading these (sometimes) large files, you might find that some don’t have any georeferencing. Most likely these files are in an image format supported by Adobe Photoshop(e.g. JPG or TIF) and you can georeference it using the Geographic Imager Georeference tool.

These are the requirements to georeference an image:

  1. Knowing the coordinate system of the image (e.g. Mercator projection, State Plane system Alabama East, UTM system NAD 83 Zone 17 N..etc)
  2. Finding three or more points from the image to assign coordinate values to each of them. These points are known as ground control points.

The first thing you need to know is the coordinate system or projection of the image you are georereferncing. If you are unsure about which coordinate system the image uses, contact the data provider or search the metadata of the image on the Internet. If you cannot get the information of the coordinate system assigned to the image, you might want to try georeferencing with different coordinate systems to make the map as precise as possible.

The second requirement is working with the ground control points. One ground control point consists of several values: 1) Pixel X coordinate, 2) Pixel Y coordinate, 3) Ground X coordinate (e.g. longitude), and 4) Ground Y coordinate (e.g. latitude). Furthermore, to make georeferencing easier, ground control points must be clearly identifiable in the image. Cultural features such as road intersection, a sharp corner of a lot or boundary are good examples of locations used as ground control points.

Now that you know what you’ll need, we’ll demonstrate a georeference workflow using the Geographic Imager Georeference tool and Google Earth.

Step 1: Obtain a non-georeferenced image

This image is in JPEG format and there is no georeference information associated with it. In order to transform it to another coordinate system or projection, mosaic with other images, or align the image to vector work using MAPublisher for Adobe Illustrator, the image must first be georeferenced.

An example image collected

Step 2: Obtain the required information

As indicated above, two key pieces of information are required to georeference an image: a) the coordinate system of the image and b) defining ground control points

a) The coordinate system of the image

The image, collected from Google Earth, is projected in a coordinate system called WGS84 / Pseudo Mercator (this projection is common to Web based mapping systems and is also known as Web Mercator or Google projection).

b) Defining ground control points

We’ll need to define at least three ground control points for georeferencing. Below are the steps for finding out one of the ground control points.

On the non-georeferenced image, decide which spot to use as a point of reference. It should be available on Google Earth where you’ll find the X,Y coordinate values. For the first point, we’ll use the corner boundary between the pavement and a golf course.

a ground control point selected on my image

Using Google Earth, find the exact same spot as the one decided in the non-georeferenced image. Place a point symbol to help identify the coordinate values. Record the collected latitude and longitude values. The latitude and longitude values are at the centre of the point symbol symbol in the Google Earth window.

collecting the latitude and longitude values from Google Earth

Find the coordinates of two additional ground control points. The latitude and longitude values are in decimal degree format and the coordinate system of those values are in the geodetic system “WGS84”.

collected three ground control points

Step 3: Georeference in Geographic Imager

In Geographic Imager, click the Georeference tool button Geographic Imager: Georeference in the Geograhpic Imager main panel (or choose File > Automate > Geographic Imager : Georerence). The Georeference dialog box will open.

Geographic Imager: Georeference window

First, we’ll need to set the proper image coordinate system and input coordinate system (the information from Step 2a). In the Format section, click the blue “Specify” link to open the Input Format dialog box.

Georeference: Input

Here we’ll specify two parameters: Image Coordinate System and alternate input coordinate system. The image of the coordinate system is WGS84 / Pseudo-Mercator as found at Step 2a. Click the “Specify” button to find the coordinate system from the coordinate systems list.

The option “Use alternate input coordinate system” will not have to be selected if the X,Y coordinate values are collected in the Eastings/Northings in the WGS84 / Pseudo-Mercator coordinate system. When those latitude and longitude values are collected, those values are collected in the decimal degree format and the values are in degree in WGS84. We will use those latitude and longitude values for the georeferencing. Specify the destination coordinate system as WGS84.

When the settings are made, click OK to close the Input Format dialog box. All the selected coordinate system for each setting will be indicated in the Format section of the Georeference dialog box.

Georeference : Input image coordinate system and input coordinate system

The next step is to enter the three ground control points collected from Google Earth. Click the pencil tool at the top of the Georeference dialog box and click a point for one of the ground control points collected at the previous steps Georeference : Pencil tool.

a ground control point selected on my image

As soon as one point is clicked on the preview image, it will add one row in the Georeference table. This row contains the point name, PX (Pixel x coordinate), PY (Pixel y coordinate), WX (World X coordinate), and WY (World Y coordinate).

Ground control point 1

For WX and WY, enter the longitude and latitude, respectively, for the first ground control point.

ground control 1: completed

Repeat the same steps for the second and third ground control points.

All three ground control points are entered

As soon as you enter three points, Geographic Imager will display the residual error values on the table for the accuracy assessment.

GCP Error

A residual error is the computed difference between an observed source coordinate and a calculated source coordinate. It is the measure of the fit between the true locations and the transformed locations of the output control points. A high residual error indicates possible error in either the observed source coordinates or the reference coordinates of the reference point in question.

When the error is particularly large, you may want to remove and add control points to adjust the error. As a general rule, apply several different transformation methods, select/deselect questionable points and select the method and reference points that yield the minimum residual error, assuming that the defined reference points are correct. Residual values are calculated via the associated error values between computed values and entered values through either the affine or various polynomial methods.

Once completed, the Geographic Imager main panel will indicate the georeference information of the image. Don’t forget to save the file once it is complete. Now your image is ready for any Geographic Imager function. You can also bring this image into MAPublisher for Adobe illustrator and align it to other GIS data.

Georeference information displayed on the Geographic Imager Main panel

New in MAPublisher 8.4: Image MAP Layer feature type for georeferenced images

MAPublisher 8.4 introduces two new related features: to import supported image formats directly from the MAPublisher Simple and Advanced Import dialog boxes and the Image MAP Layer feature type. To import a georeferenced image into the current MAPublisher 8.3 (and earlier) requires you 1) to create a new MAP Layer for an image to be placed, 2) use File > Place to place an image into the Adobe Illustrator document, and 3) to use MAPublisher Register Image to align with the vector work. With MAPublisher 8.4, these steps are streamlined and it will be much simpler to deal with georeferenced image files.

Below is the Simple Import dialog box. The new Format option, Image, is added to the drop-down list. Supported images include: PNG, JPG, TIF, GIF, JP2, PSD, PDD, and BMP.

MAPublisher 8.4: Import dialog window

The VancouverDowntown.tif file was selected from the MAPublisher Quick Start dataset. The source coordinate system of the image, “NAD 83 / UTM Zone 10N”, is automatically detected because it is a GeoTIFF and contains the georeference information of the image.

MAPublisher Simple Import: Coordinate System identified for the selected data

When the georeferenced image is imported by MAPublisher, it is stored in a new layer called “VancouverDowntown_image”. MAPublisher 8.4 introduces a new MAP Layer feature type called “Image”, a purple icon with the letter ” I “. From now on, all images should be placed on Image MAP Layers.

MAPView: New data type "IMAGE"

Remember that images placed in Adobe Illustrator using MAPublisher cannot be transformed or reprojected into another coordinate system. To transform an image from one coordinate system to another, it must be done using another software such as Geographic Imager.

MAPublisher 8.4 will be released very soon. Thanks for sending us feature requests like this one. If you have any feature requests for MAPublisher, Geographic Imager or PDF Maps, please feel free to drop us a line at We’re always happy to hear from you!

How to Download USGS Maps for your iPhone, iPad or iPod Touch

If you haven’t read about it yet, USGS topographic maps for the United States are now available for download on the Avenza PDF Maps Library.

USGS topographic maps are great for viewing, reference and recreational uses such as hiking, fishing or exploring. You can download the maps beforehand (in cellular range or over Wi-Fi) and use the GPS capability (of the iPhone and iPad Wi-Fi+3G) to locate yourself on the map. These 1:24,000 scale maps include the lower 48 states, Alaska, Hawaii and the District of Columbia. All of the maps are in geospatial PDF format. Best of all, majority of the maps are lightweight meaning they download and process quickly on your device.

The process of getting USGS maps on your iOS device is simple

First, download and install the app if you don’t have it yet. Open the PDF Maps app. In the map list screen, tap the + button (Add Map) in the top-right corner.

open the PDF Maps app

Then tap the From Avenza PDF Maps Library button.

open the PDF Maps Library

The app connects to our PDF Maps Library server and lists several categories. Tap the USGS Topographic Maps category.


The maps are categorized by state and area. We’ll retrieve a topographic map of a part of the city of Tucson, AZ. In the list of the U.S. states, tap Arizona.

Tap Arizona

In the preview map of Arizona, area grids are represented by the dashed gray lines. These area grids contain all of the available topographic maps categorized further by area name. Tap the area grid that contains Tucson.

Tap Tucson

Scroll down the list and tap Tucson East. This will take you to a preview of the map before the last step of downloading it.

Tap Tucson East

A preview of the map is shown. Finally, tap the Download 3.3MB button to download the Tucson East map. The PDF file size is listed as 3.3 MB.

download the map

The device automatically returns to the PDF Maps app where the Tucson East map will be downloading. After the download is complete, the app will automatically process and render all the tiles you’ll need to explore the map. This will only take a few minutes.

PDF Map downloading PDF Map processing

When the processing is completed, it will show it’s total size (18.1 MB) that includes tiles for all of the different zoom levels. Tap the Tucson East map to load it.

Done processing Explore map

These USGS maps and other maps on the Avenza PDF Maps Library are fully georeferenced and compatible with PDF Maps. Still have questions about PDF Maps? Read our support page or send us your questions. Stay tuned for more content.