Create Map Presentations
Lesson content
Lesson 1 of 1
Create Map Presentations
In this quick guide, you will:
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Open and display an aerial orthophoto in ENVI. * •
Add a grid line annotation to the orthophoto, and edit its properties. * •
Modify the default North arrow to use a different style. * •
Create a screen capture of the view. * •
Export the view to a full-resolution, 24-bit TIFF image.
Sample Data
Download sample data below. Then extract the contents of the .zip file to a local directory.
[GettingStarted.zip
116 MB
DownloadArrow down with horizontal line beneath it](assets/GettingStarted.zip)
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Select File > Open from the Menu bar. An Open dialog appears. 2. 2
Go to the location where you saved the sample data. Select CentralParkOrthophoto.dat and click Open. The center of the image is displayed at full (100%) resolution in the Image window. 3. 3
Click the Zoom drop-down list in the Toolbar and select 12.5% (1:8).
This is a true-color High Resolution Orthoimage from the U.S. Geological Survey.
Add Grid Lines
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Click the Annotations drop-down list in the Toolbar and select Grid Lines. Yellow grid lines and labels are added to the display. The values are in State Plane coordinates. Next, you will modify the grid line properties to use geographic coordinates and different styles for the lines and text. 2. 2
Grid line properties are displayed beneath the Toolbox in the lower-right corner of the ENVI application. Click in the white space next to the Coordinate System property and click the arrow icon. The Select Coordinate System dialog is displayed. 3. 3
Type WGS 1984 in the search field of the Select Coordinate System dialog, and press the Enter key. 4. 4
Double-click WGS 1984 in the search results.
The coordinate system changes to GCS_ WGS_1984, and the Select Coordinate System dialog is dismissed.
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Modify the following grid line properties, while leaving the remaining properties at their default values:
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X Spacing: 0.002 * •
Y Spacing: 0.002 * •
Text Font Style: Normal * •
Text Font Size: 12 * •
Background Method: None * •
Text Color: black * •
Geographic Format: Degrees * •
Geographic Precision: 2 * •
Grid Color: black * •
Grid Thickness: 2 * •
Grid Linestyle: solid line
Modify the North Arrow
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From the Menu bar, select File > Preferences. 2. 2
Click North Arrow in the list of items on the left side of the Preferences dialog. 3. 3
Click in the Symbol field, then click the small arrow that appears. 4. 4
Select a different north arrow symbol and click OK.
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Click OK to dismiss the Preferences dialog.
Create a Screen Capture of the View
In the following steps, you will create a screen capture (also called a chip) of the contents of the Image window. The options under File > Chip View to will preserve any display enhancements such as brightness, stretch type, etc. They also capture any annotations that are visible in the view.
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With the zoom percentage at 12.5%, resize the ENVI application so that the image and grid lines fill up the Image window and no white space is left; for example:
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From the Menu bar, select File > Chip View to > File. The Chip to File Parameters dialog appears. 2. 3
From the Output Format drop-down list, select JPEG. 3. 4
Select an output filename and location for the screen capture. 4. 5
Disable the Display result option. 5. 6
Click OK. 6. 7
Open the new JPEG file in a separate image or photo viewing application to verify that it looks good. 7. 8
Optionally experiment with chipping the view to PowerPoint, ArcGIS Pro (if you have it installed), Geospatial PDF, and/or Google Earth.
The Chip View to options are best used for taking a quick snapshot of the contents of a view; for example, to send via e-mail or to embed in a PowerPoint presentation. However, these are not ideal options when creating publication-ready images, posters, or PDF files. In these cases, you will likely want to create an output image that preserves the original resolution of the input image. You will learn how to do this next.
Export a Full-Resolution View to an Image File
The File >Export View to > Image File menu option exports the contents of a view, or the entire dataset extent, to a red/green/blue (RGB) 24-bit image file in ENVI or TIFF format. It preserves any annotations and image enhancements you add; however, it does not preserve the north arrow.
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Click the Grid [GCS_WGS_1984] layer in the Layer Manager to make it the active layer. 2. 2
Change the Text Font Size property to 18. 3. 3
Change the Grid Thickness property to 1. 4. 4
Select the CentralParkOrthophoto.dat layer in the Layer Manager. 5. 5
Click the Zoom drop-down list in the Toolbar and select 100% (1:1). The image zooms to its full resolution. You do not have to pan to any particular location. 6. 6
Click the Zoom drop-down list in the Toolbar and select Use Map Scale. Note the map scale that is listed; for example:
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From the Menu bar, select File > Export View to > Image File. The Export View to Image File dialog appears. 2. 8
Click theFull radio button for Output Extent. You will export the full extent of the dataset to an image file. 3. 9
Leave the Map Scale 1, Pixel Size, and Zoom Factor fields at their default values. 4. 10
Click the Output Format drop-down list and select TIFF. 5. 11
Select an output filename and location for the full-resolution TIFF file. 6. 12
Disable the Display result option.
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Open the new TIFF file in a separate application to verify that it looks good. It should contain the entire dataset, including the grid lines. When viewed at 100% resolution, the grid line labels have a font size of 18 points. You can go back and increase the font size, if desired.
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Right-click on the Grid layer in the Layer Manager and select Remove.
Two similar options are also available:
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File > Export View to > Geospatial PDF: This option lets you control the print resolution and page size for PDF output. * •
File > Export Selected Layer to TIFF: This option exports a single image layer displayed in the view to a TIFF file. It saves the entire image extent, including any enhancements (except for sharpening) at full resolution. No other layers are retained such as annotations or vectors.
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This concludes the exercise.
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