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Geographic Imager: Create shaded relief from a DEM

With Geographic Imager 3.x, you can import DEM files to Adobe Photoshop and can create shaded relief images.

step 12: Shaded relief image completed

There are two methods to achieve this:

Method 1: Run the pre-made JavaScript and apply it to all images

After opening your DEM image, choose File > Scripts > Browse… and select Shaded Relief.jsx from the SampleScripts folder inside the Geographic Imager Tutorial folder. It will generate the shaded relief image for the opened DEM image based on the settings in the JavaScript file.

 

Method 2: Create shaded relief images manually

We’ll use the DEM file Rocky Mountains.dem available in the Geographic Imager Tutorial folder for this demonstration.

1) Open the Rocky Mountains.dem image from the Geographic Imager tutorial folder. Geographic Imager automatically detects it as a DEM file and provides the option to select the DEM image import method. For this demonstration, choose Auto-Stretched from the Select Schema drop-down list.

Step 1: Import DEM file option

The imported DEM is opened in black and white. Take a look at the header of the image (or tab of the image file). Notice that it displays “Gray/16”. This indicates that the image is in the 16 Bits/Channel Grayscale mode.

step 1: Imported DEM image

2) Now, change the image mode from 16 Bits/Channel Grayscale to 8 Bits/Channel RGB. From the top menu bar, choose Image > Mode and then 8 Bits/Channel. Once again, go to Image > Mode, this time choose RGB Color.

step 2: Changing the color mode

Once completed, take a look at the image header again (or file tab). Now “RGB/8” is indicated in the header, meaning that the image is now in the 8 Bits/Channel RGB color mode.

step 2: Color mode changed

3) Select the entire canvas (use the Rectangular Marquee Tool) and copy the selected area to the clipboard (Edit > Copy).

step 3: Select the entire canvas

4) Open the Channels panel (Window > Channels) and add one Alpha channel by clicking the Create new channel button at the bottom of the panel or go to the panel option menu and choose New Channel. Leave the channel name as “Alpha 1”.

step 4: create a new channel

5) Select the “Alpha 1” in the Channels panel and fill it in white using the Paint Bucket Tool.

step 5: Filling Alpha channel

6) In step 3 we copied the selected area (the entire canvas) to the clipboard, now we’re going to paste it to the new channel. Select “Alpha 1” in the Channels panel, and paste it (Edit > Paste). You can see that the same image is displayed for all the channels when the copied area is successfully pasted. Make the Alpha 1 channel invisible and make sure the RGB channels are visible.

step 6: pasted canvas

7) Deselect the area (Select > Deselect from the top menu bar).

step 7: deselected area

8) In the Layers panel (Window > Layers), create a new layer named Bump map. Change the Blending mode to Overlay. step 8: New Layer "Bump map"

9) Using the Paint Bucket Tool again, fill the new “Bump map” layer with white.

step 9: fill white

10) From the menu bar, choose Filter > Render > Lighting Effects…

step 10: Menu Filter > REnder > Lighting Effects ...

11) Adjust the settings in the Lighting Effects dialog window.

step 11: adjusting the light effect

12) The shaded relief image is completed! You can use this image to overlay with other georeferenced images with Geographic Imager or with vector datasets with MAPublisher.

step 12: Shaded relief image completed

Create a New MAP View For Adobe Photoshop Paths in MAPublisher 8.3

In our previous blog, we introduced you to a quick technique for remote sensing imagery: to depict a type of land types (green area) from a Landsat image. Below is the false composite image created in the previous blog. Basically, the red area indicates a lot of green vegetation (i.e. trees, shrubs, etc).

False color composite image produced in the previous blog

Now, you may be wondering how those red areas can be extracted from Adobe Photoshop and Geographic Imager and brought into Adobe Illustrator and MAPublisher?

An overview of the steps involved in this technique:

In Adobe Photoshop & Geographic Imager:

  1. Select the red areas with Adobe Photoshop tools.
  2. Save the selected pixel areas as “work path”.
  3. Export the saved work path as an Adobe Illustrator file.
  4. Export the georeference information from Geographic Imager option menu.

 

In Adobe Illustrator & MAPublisher:

  1. Import the exported Adobe Illustrator file with the work path.
  2. Assign the georeference information to the imported work path objects.
  3. If you have already made a map with vector dataset, open the AI file.
  4. Import MAP Objects from the AI file with the workpath to another AI file with a map.
  5. Drag and Drop transformation to align the workpath objects geospatially.

 

Below are the detailed step-by-step intructions.

In Adobe Photoshop and Geographic Imager:

1. Select the red areas

Open the false color composite image in Adobe Photoshop. Now, all the red areas must be selected using any of the following Adobe Photoshop tools.

Selected red areas

For example, you can select the red areas using the Magic Wand Tool. You may want to adjust the tolerance values as you begin to select the areas so that only the approriate areas are selected. If you disable the “Contiguous” option from the settings tool bar, it selects all the areas with the same color as the one you collected.
Magic wand tool settings

If you want to more precisely select red areas with a preview window, use the Color Range Tool (Select > Color Range). With this tool, sample the color of interest first. In this example, you might want to pick only the areas with the bright red color or you might want to be within a specifc range of red. Using this, you will have more control on which areas are selected.

Photoshop Tool: Color Range

Of course, there are other techniques you can use to collect the pixels with a specific color. The two suggested above are used quite commonly in our workflows.

2. Save the selected pixel areas as “work path”

After all the red areas are selected, save the selected area as “work path”. This option is available in the Paths panel options menu.

Save the selected areas as Work Path

The selection is now saved as a “work path” in the Paths panel.

Saved work path in the Paths panel

3. Export the saved work path as an Illustrator file

Once the work path is saved in the Paths panel, export it as an Illustrator file (File > Export > Paths to Illustrator).

Save the work path as an Adobe Illustrator file

4. Export the georeference information from Geographic Imager option menu

As you saw in the Geographic Imager panel for the false color composite file in the previous blog, this image was georeferenced. Furthermore, we need to export the georeference information that will coincide with the Adobe Illustrator file we just exported.. You can export this georeference information as a MapInfo TAB file or Blue Marble Reference RSF file from the Geographic Imager panel options menu.

Export the georeference information from the Geographic Imager panel

In Adobe Illustrator & MAPublisher

5. Import the exported Illustrator file with the work path

In Adobe Illustrator, open the Adobe Illustrator file exported from Adobe Photoshop (Step 3). Upon opening, a prompt appears to convert the exported file to Artboards. Select the second option “Crop Area(s)”.

Opening the exported Adobe Illustrator file.

When the artboard is opened, it seems like there is nothing on the artboard. It is simply because there is no color assigned to the fill and stroke. I put a green color for the work path objects.

Imported exported Adobe Illustrator file.

6. Assign the georeference information to the imported work path objects

The imported work path objects do not have the georeference information yet. We exported the reference file in Step 4 using Geographic Imager. We are going to use the exported reference file to assign the georerefernce information to those work path objects.

In the MAP Views panel options menu, click “New MAP View For Photoshop Paths…”

MAP Views option: Create a MAPView from Photoshop path

Browse for the exported reference file (either *.tab or *.rsf format from Step 4). Then select “Area” as the feature type for the MAP layer to be created.

MAPublisher dialog: New MAPView For Photoshop Paths

The georeference information from the original image is now inherited by the work path objects in the Adobe Illustrator file.

A created new MAPView

In the MAP View Editor window, you can see all the spatial information such as the coordinate system, scale, and map extent within the artboard. The name for the MAP View is renamed to “Green Area from Photoshop – GI” for Step 8.

At this point, if you have GIS dataset, you can import them to this document. However, I will show you one more MAPublisher trick to bring this green area into an existing MAPublisher file.

The georeference information in the MAPView editor

7. If you have already made a map with vector dataset, open the Adobe Illustrator file

Keep the Adobe Illustrator file with the work path objects open, then open another Adobe Illustrator file with MAPublisher MAP Objects. Now you have two Adobe Illustrator documents open.

8. Import MAP Objects from the AI file with the workpath to another AI file with a map

Make the Adobe Illustrator document with the map (not with the work path objects) the current document.

On the MAPublisher Toolbar, click the “Import MAP Object” button.

In the “Import MAP Objects” dialog box, select the MAP View “Green Area from Photoshop” and click OK.

Imported MAPView with a MAP layer

All the path objects are imported to the other Adobe Illustrator file with the base map.

Imported green area from another Adobe Illustrator document

However, the imported objects and the base map do not line up appropriately. It is because the scale of the MAP View with the work path and the MAP View with the base map do not match. You can line up those green areas with a simple step.

9. Drag and drop transformation to align the workpath objects geospatially.

In the MAP Views panel, there are two MAP Views: “Green Area from Photoshop – GI” for the work path imported from another AI file and “Toronto map” for the base map.

Click the MAP Layer “Green areas” in the MAPView “Green Area from Photoshop – GI” …

MAPublisher special trick: Drag and Drop transformation

… then drag the map layer to the MAPView “Toronto map”.

Transformed MAP Layer

Now all the green areas (work path objects) are lined up nicely with the base map.

Green areas in Toronto nicely lined up with the base map.

Try this out with your own workflow to see how it may improve your maps.

Creating a false-color composite image with Geographic Imager for Adobe Photoshop

One of the powerful remote sensing tools available in Adobe Photoshop is to detect the land surface information by creating a false color composite image. Multispectral images contain the reflectance information from the visible and invisible electromagnetic spectrum. Using this information, we can detect many kinds of land surface information. For this example, we will detect the green area using Landsat images imported by Geographic Imager for Adobe Photoshop, which ensures all the georeference information is maintained.

Landsat images consist of several gray scale images, with each image containing one of the bands of the electromagnetic spectrum. For example, in the Geographic Imager tutorial folder, there are a set of Landsat images available. Those gray scale images are from Band 1, 2, 3, 4, 5, 7, and 8.

Landsat Images available in the Geographic Imager tutorial folder

These images need to be combined into one image. The Adobe Photoshop function called “Merge Channels” produces one image by combining mulitple gray scaled images. With this example, those gray scale images from Band 2, 3, and 4 will be merged into one image by assigning a color for each band.

Image analysis trick

1) Open the Landsat image from Band 2, 3, and 4. Note that the Geographic Imager panel shows the information on the coordinate system and image extents.

Georeference information on the Geographic Imager panel

2) Open the Channel panel (Window > Channels). Choose “Merge Channels” from the panel options menu.

Merge Channels

3) In the Merge Channels dialog box, select RGB color as the mode.

Merge Channels - RGB

4) In the Merge RGB Channels dialog box, specify the band for each channel: band 4 for the red channel, band 3 for the green channel, and band 2 for the blue channel.

Specifying the channels for Merge channels

5) As a result, those three images from Band 2, 3, and 4, are assigned to the Blue, Green and Red channels, respectively.

Merge channels result in the Channels panel

6) Now, let’s take a look at the image!

Merge channels result - false color composite image

This combination of false-color makes vegetation appear as red tones. The bright red color indicates the growing vegtation. Water is displayed in a blue color. When the water contains high sediment concentrations, the color will be lighter blue. Urban areas will appear gray to blue-gray in color.

7) All the georeferenced information is inherited by the new image with merged channels from those original images. The georeference information is displayed in the Geographic Imager panel.

The georeference information was maintained from the original georeferenced image.