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Using Overlays


Beginner Tutorial

With the latest update to Google Map Maker: the "Overlay" feature, you can now add your own maps and images on top of the regular map to help orient yourself and guide your mapping.

1. Find or Make Content
To access KML maps or Images in Google Map Maker with the Overlay feature, this content will need to be online and you will need its web address. In this tutorial, we will use a KML map already online from Panoramio, a Google-run website where users can share geotagged photos. To find more KML or Image data try a Google Search or see below for tips on how to add your own content to the web. 


2. Add Content to Map Maker
Once you have a web address for the content you'd like to see in Google Map Maker, you can add this web address to your Overlays. To do this, first go to the Google Map Maker homepage: http://mapmaker.google.com and sign in using your Google Account. Next, click on the "Overlays" tab on the upper-right hand corner of the map view. (see image below)

Click the "Manage overlays" button. This will open a window where you can add KML and Image web addresses. For this tutorial, copy the following Panoramio KML url text: www.panoramio.com/kml  , enter it under the section that says "KML:" in the dialog box, and click "Add". (see image below) When you are finished managing your overlays, simply click "OK".



3. Enjoy Mapping with new Data!

If adding the web address of the Panoramio KML file has worked, you will see the image below. When zooming in, you may need to pause in an area for some time for the KML file to load. Overlays will only be kept while you have Google Map Maker open your web browser as they are not stored with your user account.  If you close or refresh your browser, you will need to repeat the steps above again to see your Overlays.


Click the "Overlay" button to turn on and off the overlays. Click the "Manage overlays" link again to add and remove your overlays. If you want to add more URLs, you can continue to enter them one at a time under the appropriate "KML" or "Image" field and click "Add". To remove a link, simply click on the boxed "X" next to the URL you'd like to remove. Connecting to too many links may slow down your Map Maker connection.

You can now turn on and off the Overlays tab as you like in order to better help you map. Panoramio photos are great for helping you see what areas look like on the ground. This will let you orient yourself when looking at the world from above as well as give you ideas of what additional landmarks, points of interest, etc. may be worth adding to the map. Happy Mapping!


Advanced Tutorial

Adding Your Content to the Web

There are many types of data you may want to add online in order to access it from Google Map Maker. Also, be sure to share links to non-private files with fellow Map Makers so they can also help map by posting links to them on the Map Maker Groups page.


Where to Host Content
Videos: YouTube (Can embed videos in KML file)


Types of Content to Add

Geotagged Picasa Photos

You can put your own photos on a map using Google Picasa photo service. Once you have your photos geotagged and online, get the URL link to the KML by right-clicking the "View in Google Earth" link and copying the link address location.

My Maps

You can draw personalized maps on top of Google Maps by using its My Maps feature. If you'd like to be able to see these maps in Google Map Maker in addition to Google Maps, open the My Map and then get the URL link to the KML by right-clicking the "VIew in Google Earth" link and copying the link address location.


GPS Tracks

You can now open GPS files with the free version of Google Earth. This will cause the GPS files to be converted to KML files, which you can then save to your computer. To put this KML file of your GPS tracks online, upload them as My Maps on Google Maps. (see how in the below section on "KML Files".)


KML Files

To put your KML files online, you can upload them as My Maps on Google Maps. First go to the Google Maps website: http://maps.google.com , and click "Sign In" in the upper right-hand corner. You will need a free Google Account to sign in. From there click on the "My Maps" tab in the left-hand panel. Then click on the "Create a new map" link under the My Maps tab and then the "Import" link. (see below) This will open a window where you can point to the KML on your computer and upload it to a My Map. Once uploaded, you can get the URL for the My Map KML by right-clicking on the "View in Google Earth" link and copying the link address location. (see above)

Digitized Map Images

In addition to linking to KMLs, you are also able to link to Images when you manage your Map Maker Overlays. As an exercise, use a map image URL copied after right-clicking a map image from the CIA World Factbook, a public domain almanac put together by the United States government. For example, here's the URL for the map of Angola: https://www.cia.gov/library/publications/the-world-factbook/maps/ao-map.gif . You may also choose to scan or take a photograph of your own maps, such as a map you may have drawn or annotated by hand. There are three things to keep in mind while using Image Overlays:
Sizing and Placement
After entering an image url as an Overlay, you can grab the white squares to resize and move the image until it roughly aligns with the map underneath it, but you will need to do this alignment each time you want to use this image, as Map Maker does not remember your Overlays once you close or re-load your browser. If you have actual GPS points to anchor the image or you plan on using the image often, you may want to consider making a Ground Overlay KML file with these coordinates or simply sizing it by hand once in Google Earth and then adding the information as an online-hosted KML file you can point to instead of an image overlay.

Transparency
Often, it helps to adjust the transparency of your map image so that you can see the Map Maker map underneath your image and align your image appropriately. Unfortunately, there is currently no way to adjust transparency of an image using Map Maker. You can, however, adjust transparency of an image file by turning it into a .png file and adjusting opacity using a separate program, such as GIMP or Photoshop, and then uploading that image online. For instance, here is a link to the same image of CIA World Factbook map of Angola linked to above with 70% opacity that was uploaded to Picasa Web Albums you can try out with the Map Maker Overlay feature:
http://lh3.ggpht.com/_X38dmmWol7c/SgoHindyPBI/AAAAAAAAABc/7ciLsDpgRWM/cia_wfb_angola.png

Copyright
Remember that your use of Map Maker and this feature is subject to the Google Map Maker Terms of Service.