Subsetting An Image And 3d Rendering

Lab Materials

Download this: Lab Materials

Lab Content

Objective

Students will subset an image.

Procedure

Creating A Subset Image In Erdas Imagine

  1. Pull up the image LC80180362013116LGN01 that you created for the Compositing Images lab into an Imagine viewer. Click on the ‘i’ button on the viewer toolbar to get the coordinate/projection info of the image.

    ../_images/InformationButton.png

  2. Pull up the HUC12 watershed boundary shapefile, HUC12_031300010305.shp, from the LabMaterials folder. Click on the ‘i’ button on the viewer toolbar to get the coordinate/projection info of the shapefile.

  3. Make sure that the image to be subset, and the shape file to be used for the ‘cookie cut’ have the same projection and datum. If not, use ArcTools to reproject the shapefile to the same projection as the image.

  4. Select the viewer that the shape file is in and go to the File–> New –> 2D View –> AOI Layer.

  5. In the viewer where you have the shapefile, click on the shapefile and it will turn to a different color to indicate that it has been selected (yellow).

  6. Select the AOI layer that you just made (by clicking on it once over in the contents window) and go to the drawing tab and then over to the box that says Edit and click on the Paste from Selected Object icon.

    ../_images/PasteFromSelectedObject.png

  7. Save the AOI layer to your folder. This is done by right clicking on it in the Content window and selecting Save Layer As.

  8. Go to the Raster tab and then to Subset & Chip, then click on Create Subset Image.

    ../_images/SubsetImageButton.png

    ../_images/SubsetMenu.png

  9. Save the output File as watershed.img. Click on AOI and check the box for File and specify it to be the AOI layer that you saved earlier. Click Ok and run the process, once finished open up the output and check to make sure the process was done correctly.

Creating A Subset Image In ArcMap

  1. Pull up the image LC80180362013116LGN01 that you created for the Compositing Images lab into ArcMap. Right click on the image in the table of contents and click properties and then source to get the coordinate/projection info of the image.

  2. Pull up the HUC12 watershed boundary shapefile, HUC12_031300010305.shp, from the LabMaterials folder. Right click on the shapefile in the table of contents and click properties and then source to get the coordinate/projection info of the layer.

  3. Make sure that the image to be subset, and the shape file to be used for the ‘cookie cut’ have the same projection and datum. If not, use ArcTools to reproject the shapefile to the same projection as the image.

  4. Before we can clip the image we have to make sure that the spatial analyst toolbar is turned on. To do this you have to click on the Customize tab and then extensions. Check all of the boxes here so you do not have to worry about running into any issues.

    ../_images/SpatialAnalystBox.png

  5. Use the search functionality to find and open the Clip (Data Management) tool.

  6. Set the inputs on the tool and make sure they match the highlighted sections in the picture below. To learn more about what each option does click the Show Help button and as you click on the different elements of the tool it will explain what each one is. Save the output File as watershed2.img.

    ../_images/Clip.png

  7. Open up one of your subset images in ArcMap and do a map composition. It should look similar to the MossyCreek.PDF document in the LabMaterials Folder you downloaded.

Creating A 3-D Image Rendering

  1. Open a new 3D view in Erdas Imagine by going to the File menu and clicking new –> 3D view.
  2. Right click on 3D View #1 in the Contents window and select Open DEM…
  3. Open the DEM from the Lab Materials folder into the 3D view by right clicking on 3D view #1 in the contents window and clicking add DEM.
  4. Right click on 3D View #1 in the Contents window and select Open Raster Layer.
  5. Navigate to watershed.img which once selected will drape the image over the DEM. Note that these two files are in the same coordinate system and based on the same datum; i.e. both of these files are in ‘register’ with each other. This is a necessary condition for image draping.
  6. Right click in the viewer and play with the different ways to pan or fly through the image and note your observations.
  7. Click on the Scene tab at the top of the screen and this will open tools for use in the 3D viewer that you have open.
  8. Click Scene Properties and experiment with the following vertical exaggeration values and note your observations:
    1. 0.5
    2. 1.5
    3. 2.0
  9. Include a screenshot of the 3D rendering as well as your observations in your lab report.

Metadata

Title:Subsetting An Image And 3d Rendering
CreationDate:10/07/2013
SoftwareUsed:ArcMap, Erdas Imagine
SoftwareVersion:10.1, 11.0.3
Contributors:Brandon Rumiser, JB Sharma, Zac Miller