Google Maps Engine

Make a map with image data An online HTML version of this tutorial is available here in the Google Maps Engine Help Center. This tutorial shows you how to build a map from image data using Google Maps Engine. To build a map from vector data—points, lines, and polygons—see the companion tutorial, Make a map with vector data. To build the map in this tutorial, we'll do the following: Upload sample image data. Create an image mosaic. A mosaic joins two (or more) images that show adjacent areas into one seamless image, for ease of handling and display. Add the mosaic to a layer. Add the layer to a map and publish it.

About the sample file The source images for this tutorial, made available by the Cal-Atlas Geospatial Center , are two digital topographic maps showing the regions north and south of the San Francisco Bay Area. Maps Engine will splice these two maps together into one mosaic, then align it with the underlying base map of California.

1. Sign in and prepare files To get started: 1. In your Internet browser, go to mapsengine.google.com

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2. Sign in to your organization's Google Maps Engine project. 3. Download the Google_Maps_Engine_Tutorials_Image_Data.zipfile, which contains a sample dataset for this tutorial. 4. Unzip this file to a working directory on your computer. If you need a zip or unzip utility for your PC, see www.7-zip.org. The sample datasets are in the MrSID format, where each SID file has an AUX and SDW file that go with it. You should have the following files: sf_bay_north_topo.aux sf_bay_north_topo.sdw sf_bay_north_topo.sid

sf_bay_south_topo.aux sf_bay_south_topo.sdw sf_bay_south_topo.sid Now you're ready to upload data to Google Maps Engine!

2. Add attributions Before uploading image data, you should create an attribution, which gives credit to your data sources. Once you’ve created an attribution, it’s stored by Maps Engine and can be applied to any image data you upload in the future. Note: Attributions are only needed for image or terrain data sources; they aren't used for vector data. Follow these steps: 1. Click Create at top left, then select Attribution from the drop-down list.

2. For the attribution Title, enter USGS and CDFG. 3. For the Display text, enter U.S. Geological Survey & California Department of Fish and Game 4. Click Save. To see all attributions you’ve created, click Attribution in the left panel. To edit or delete an attribution, click it to open the Edit attribution details dialog box. Note: You can't delete an attribution that has been associated with any datasets. You must first edit the Data details for those datasets to remove the attribution. Once you've done that, a Delete button displays in the Edit attribution details dialog box.

3. Upload image data

About image data Image data—also called raster data—is composed of rows and columns of pixels, arranged in a grid. Viewed up close, individual pixels look like solid dots of color, but grouped together and seen from farther away, they can form clear and recognizable images. Image data used in maps can come from a variety of sources: satellite or aerial photography, street level photography, or even hand-drawn material that's been digitized. Maps Engine supports image data in many formats, including JPEG, TIFF, JPEG2000, GeoTIFF, and MrSID. The source data for this tutorial is two digitized topographic maps of the San Francisco Bay Area and adjacent areas of California. There is one map for the northern section, and one for the southern section. Because you can only upload one raster dataset at a time, you’ll need to upload the north bay dataset first, then repeat the process for the south bay dataset. To upload an image dataset: 1. Click the red Upload icon (up arrow) in the top left corner, and select Files.

The Upload dialog box displays. 2. Click Browse and navigate to the folder where you unzipped the sample image data. 3. Select the three files that start with sf_bay_north_topo(ending with .sid, .sdw, and .aux). Tip: While selecting, hold the Shift key to select multiple adjacent files. Hold the Control key (Windows) or the Command key (MacOS) to select multiple individual files. These files together make up the north bay raster dataset. There's a main file and associated files called sidecar files, which add necessary location information. For example, the sf_bay_north_topo.sdwfile is a sidecar file, specifically a world file, which includes exact coordinate information for the image data in the main file.

Tip: Missing sidecar files can also be added later on, if the processing of the data fails. 4. Click Open to add the files to the Upload dialog box.

The Name field lets you edit the name of the dataset as you want it to appear in the Data source list in Maps Engine. For this exercise, you can leave the name as is. 5. For Description, copy the following text and paste it in: 250K Digital Raster Graphic (DRG) Mosaics. Downloaded from CalAtlas Geospatial Center. Link: http://atlas.ca.gov/download.html#/casil/imageryBaseMapsLandCov er/ baseMaps/drg/1x2_degree_series_albers_nad83_mosaic/MrSID (Data files used were c_nw0101.sid and c_sw0101.sid). 6. Tags make it easier for you and others to search for your dataset. You can enter multiple tags, separated by commas. For this exercise, enter tutorial. 7. For Attribution, select the attribution we created in the previous step: USGS and CDFG. 8. Leave the Date acquired and Processing Type settings as they are. (For more information on processing options see masking images.) 9. Click Upload. The Upload dialog box shows progress while the files are uploaded. When that's done, Maps Engine takes you to the Data details page for the dataset you just uploaded. When you first arrive at this page, Maps Engine is still processing the image data, as shown at the top of the page:

Depending on the size of your dataset, the dataset could take a few minutes to a few hours to process. After Maps Engine processes the image dataset, the message is updated:

10. Once the image has finished processing, click anywhere on the thumbnail map (right corner), or the Click to view image link under the map, to view the north bay topographic map data source in Google Maps.

11. Click your browser's back button (

⬅) to return to the Data details page.

12. Repeat Steps 1—10 for the second image dataset, and upload all the files with the prefix sf_bay_south_topo. When you've uploaded both image datasets, click Data sources in the list on the left, to show all the image data you've uploaded. Your page should look something like this:

With both pieces of your topographic map uploaded, now you're ready to combine them into a single continuous image.

4. Create an image mosaic The image datasets you uploaded are tiles, meaning they can be placed edge to edge to create a continuous image. Maps Engine can combine these separate images into an image mosaic, then treat them as a single dataset. 1. Make sure you’re still on the Data sources page. 2. Click Create > Mosaic.

The Create new mosaic dialog box displays. 3. For Mosaic title, enter Topography Base Map. 4. From the Choose attribution drop-down list, select USGS and CDFG. 5. Click Create. At the top of the page, a yellow bar tells you that your mosaic has been created.

6. In the data source area, check the boxes at the lower right of each icon to select the two

topographic map data sources.

7. Click Add to mosaic in the list on the left. 8. In the Add to mosaic dialog box, open the Select a mosaic drop-down list, and select Topography Base Map.

Tip: You can also create a new mosaic from the Add to mosaic dialog box. To do that, start at step 6 above (select your data sources), do step 7, and then click Create new in the Add to mosaic dialog box. Enter the mosaic title and choose an attribution, and then continue with the following steps. 9. Click Add to mosaic. The yellow band at the top of the page now reads Topography Base Map updated. (If you created the mosaic using the tip in step 8, this band will read Topography Base Map created.) 10. Click the View details link in the yellow band.

The Data details page shows that the mosaic is ready to process. The lower part shows the two selected images you’re adding to the mosaic. 11. Click Process now.

The message at the top changes to Mosaic is being processed. Depending on the size of the mosaic, and the number of jobs in the queue, processing may take minutes or hours. When done, the message at the top changes to Mosaic was processed.

12. To preview your mosaic, click anywhere on the map thumbnail or the Click to view mosaic link to view it in Google Maps.

While previewing the map, you can use the Transparency slider to change the opacity of the topographic data, showing more or less of the underlying base map. Click Details view, or click your browser's back button ( ) to return to the Data details page.

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Tip: You can add additional images to an existing mosaic at any time. In the Data details page for the mosaic, click the Add images link in the list on the left. Select and add images, then process the mosaic as you did above. Now that you've created and processed a mosaic image, you're ready to add it to an image layer.

5. Create and publish an image layer With your image mosaic processed and ready to go, the next steps are to create an image

layer to contain the mosaic and publish that layer. To create an image layer: 1. Make sure you’re on the Data details page for the image mosaic dataset. 2. Click Create and select Layer from the drop-down list. This displays the Create new layer dialog box. 3. For the Layer title, enter Topography. The Layer type defaults to Image to match our image data source.

4. Click Create. Tip: An alternate way to create a layer is to click the Add to layer choice under Data sources in the list at left.

Then, in the Add to layer dialog box, click Create new, fill in the new layer title, and click Add to layer.

After either method, a yellow band displays at the top of the page confirming that the layer has been created.

5. Click the View details link. Alternatively, you can click Layers in the left menu, and select your new layer to view its details page. In the Layer details page for the new layer, the message at the top reads Layer is ready to process. Remember, a new (or modified) layer must be processed and published before you can use it in a map. 6. Click Process now. 7. In the Process layer dialog box, click Process. Depending on the size of your dataset, processing can take from a few minutes to a few hours. When it's done, the Layer is being processedmessage changes to Layer has been processed. 8. After the layer is processed, click the thumbnail image at right, or the Click to view draft link below the thumbnail, to preview the layer in Google Maps.

⬅) to return to the Layer details page.

9. Click your browser's back button ( To publish your image layer

Once the layer is processed you're ready to publish it, which makes it available for use in a map. Note: This step does not publish the layer to the public.

10. Click Publish layer.

When the layer is published, the Publish layer button turns into an Unpublish layer button. 11. Click Edit details in the left column. 12. In the Edit layer details dialog box, enter a description and one or more tags for the layer. 13. Click Save. You're now back on the Layer details page for the published image data layer. The last step is to add the image layer to a map, then publish the map!

6. Add image layer to a map and publish After creating and publishing an image layer in Maps Engine, your next step is to add the layer to a map. You can then publish your map and share it publicly on the Internet, internally to your organization, or privately to trusted colleagues. 1. Make sure you're still on the Layer details page for the Topography layer that you published in the last step. If you're previewing the layer in map view, click Layer details at top right to return to the Layer details page. 2. Click Create > Map.

3. In the Create new map dialog box, enter a Map title. For this exercise, enter Bay area topographic map. 4. Click Create. You should now see a preview of your map, with your image mosaic layer visible. From this page it's easy to modify your map and its layers, using the various menus and buttons that are called out below:

Here are some of the things you can do in the future from the map preview page: Click Add layers to add more layers to your map. Click the Show layer pull-down list and use the Layers menu to view layer details, edit layer name, or remove a layer from the map.

Mouse over the map name to show the edit link, which lets you edit the map name and description.

Click Sharing

to define who has edit access and viewing access to the map.

Hover over the Base map icon and click the Change link

to

change the base map that underlies your image data layer. Click Map details view to switch to the map details page. Now you're ready to publish your map. While you can do this from the map page, we'll switch to the map details page to publish. 5. At the top of the page, click Map details view. 6. In the Map details page, click Publish map. The message at the top changes to Publishing map, then to Map was published. If you later need to unpublish this map, click Unpublish map. You're done! But remember, publishing your map does not make the map or its layers public —it only publishes the map to those users you've chosen to share the map with or make it viewable to. To go farther and make your map available to users on the Internet, see the Share your map online tutorial.

7. What's next? Go to the next tutorial: Share your map online, or you can build a different sample map with the Make a map with vector data tutorial. Check out the Maps Engine Roadmap help topic. See more tutorials focused on nonprofit use cases at the Google Earth Outreach site. Check out how organizations like World Wildlife Fund and Living Oceans Society are using Google Maps Engine!