Adding Applanix DSS data to a mosaic dataset

This topic applies to ArcEditor and ArcInfo only.

Applanix DSS is a medium-format, digital, airborne remote sensing system, using integrated inertial technology to produce georeferenced color and color infrared (CIR) imagery.

Applanix data can be added to a mosaic dataset using the Applanix raster type. When using this raster type, you must modify the properties of the raster type to define the DEM, the location of the input image, and the camera properties. It is recommended that you save your modifications to this raster type to save yourself the time of having to re-enter the information, specifically the camera properties. For example, once you've modified the camera properties, as discussed below, you can click Save As on the General tab and save the modified raster type as a .art file. Next time you can browse to the file in the Add Raster To Mosaic Dataset tool's dialog box, rather than selecting it from the Raster Type drop-down list and editing the properties once again.

The steps below describe the workflow used to create a mosaic dataset containing Applanix sensor data:

Steps:

1. Create a mosaic dataset.
2. In the Catalog window or ArcCatalog, right-click the mosaic dataset and click Add Rasters.

   The Add Rasters To Mosaic Dataset dialog box opens.

3. Click the Raster Type drop-down list and click Applanix.
4. Click the Edit Raster Type Properties button .

   The Raster Type Properties dialog box is opened. Here you will enter specific information about the DEM and camera.

5. Click the Camera Definition tab to define the camera information, which is often found in a file supplied by the data or camera vendor.
6. Click the Camera Model drop-down and make a selection.

   This will set any predefined parameters for the chosen camera model. The following camera models are available:

   Camera model	Defaults
   DSS 322	Number of Pixels (Columns): 5436 Number of Lines (Rows): 4092 Pixel Size (Microns): 9
   DSS 439	Number of Pixels (Columns): 7216 Number of Lines (Rows): 5412 Pixel Size (Microns): 6.8

   Applanix DSS camera models

7. Enter a value for Focal Length and choose the correct units.
8. Enter the principal point of autocollimation along the x-axis in the PPA X text box and choose the correct units.
9. Enter the principal point of autocollimation along the y-axis in the PPA Y text box and choose the correct units.
10. Click the Type of Distortion drop-down arrow and choose either Konrady Coefficients or Radial Distortions.
    • If you chose Radial Distortions, a table will appear where you can enter the values provided in the camera calibration report. This is the recommended method. Once you've entered the values in this table, you can view the calculated coefficients by changing the Type of Distortion method to Konrady Coefficients.
    • If you chose Radial Distortions you need to click the Radial Lense Distortion Coefficient Method drop-down arrow and choose one of the options:
      • Konrady (ESRI)
      • Konrady (USGS)

      This may already have been applied by the camera's postprocessing software. Please verify this distortion value is needed. If it is not needed, leave the 0 value defaults.

      ArcGIS uses Konrady coefficients to calculate radial distortion correction for standard frame cameras. These coefficients model the radial distortion as a function of the radial distance from the center (r) as a power sequence. There are two ways these coefficients can be applied, USGS Konrady and ESRI Konrady. They differ in how they use the coefficients, so the method used should match the way the coefficients were derived.

      The ESRI equation is

      error = K1 + K2 * r2 + K3 * r4

      The USGS equation is

      error = K1 + K2 * r3 + K3 * r5

      where K1, K2, and K3 are Konrady coefficients and r is the radial distance from the center.

11. Click the General tab.
12. Check your exterior orientation file. If the extension is not .txt you must enter it in the Filter text box. For example, if it is .dat, change the .txt to .dat.
13. Optionally, by clicking the Save As button, you can save these changes to the raster type by saving the raster type to a file which can be reused in place of the Applanix raster type in the drop-down list.
14. Click the Properties tab to set the properties used to define the elevation model used in the orthorectification of the imagery.

    Tips for using a DEM:

    • If your DEM is smaller than the extent of the collection of images, the images will be cropped to the extent of the DEM. Also, the DEM impacts the orthorectification, so it is best if the DEM is at least as large, in extent, as the collection of images.
    • Make sure the spatial reference system in the exterior orientation file and the DEM are the same; otherwise, you may have to modify the DEM by either checking the Geoid check box or entering z offset and factor values. Optionally, you can apply a geoid correction to your elevation data by creating a mosaic dataset containing the elevation data and using the Arithmetic function to apply the required equation. For specific steps, see Converting from orthometric to ellipsoidal heights.

    • You can use a DEM stored as a raster dataset (in any ArcGIS supported raster format), stored in a raster catalog, a mosaic dataset, an image service, or WCS service.

    • If you have multiple DEM raster datasets you can add them to a mosaic dataset to create a single dataset that can be used as the DEM.

    • If the format has a NoData value this is supported. You can verify the NoData value in the raster properties of your raster dataset. If you need to convert a value to NoData, use the Copy Raster tool and define a value for the NoData Value parameter. This tool will output a new raster dataset. If you do not want to create a new raster dataset, you can add your DEM to a mosaic dataset and use the Define Mosaic Dataset NoData tool to define the NoData value. Using this method you can define more than one value to be interpreted as NoData.

15. Click the Orthorectification using elevation radio button to choose one of the methods:

    DEM	Choose the DEM from a raster dataset, mosaic dataset, image service, or WCS service you want to use for orthorectification.
    Constant elevation	Enter the value of the constant (average) elevation for the area covered by the images.
    Average elevation	Average elevation does not apply to Applanix data; therefore, do not use this.

16. Optionally, you may need to set the Elevation adjustment parameters.

    Z offset	The base value to be added to the elevation value in the DEM. This could be used to offset elevation values that do not start at sea level.
    Z factor	The scaling factor used to convert the elevation values. The scaling factor is used for two purposes: first, to convert the elevation units (such as meters or feet) to the horizontal coordinate units of the dataset, which may be feet, meters, or degrees, and second, to add vertical exaggeration for visual effect.

17. Click the Auxiliary Inputs tab to define the folder location of the imagery.
18. Click the browse button, navigate to the folder containing the input images, then click OK.
19. Click OK to close the Raster Type Properties dialog box.
20. Click the Input drop-down arrow and click File.
21. Click the browse button , navigate to the exterior orientation file (.txt), and click Open.

    The text file is added to the Source list.

    For specifics about the exterior orientation file, see Applanix exterior orientation file.

22. There may be some additional information you need to define within the Advanced Options section, although it is not always necessary. For example:
    1. If the spatial reference for the input data is different from the mosaic dataset, you will need to define it with the Coordinate system for Input Data parameter.
    2. If the data does not have pyramids or statistics, you can calculate them by checking Build Raster Pyramids and Calculate Statistics. This is highly recommended.
23. Click OK to run the tool and add the Applanix DSS data to the mosaic dataset.

The footprints created are simple polygons to define the four corners of the unorthorectified image. You should modify the footprints to match the shape of the orthorectified image, before building overviews. These steps are shown next.

Recalculating the footprints

Steps:

1. Open the Build Footprints tool.
2. Browse to the mosaic dataset, or click the Mosaic Dataset drop-down arrow to choose the mosaic dataset layer.
3. Change the Minimum Data Value and Maximum Data Value low and high extents of the bit depth, such as 0 and 255 for 8-bit data.
4. To shrink the footprints specify a Shrink Distance value.

   This value is specified in the units of the mosaic dataset's coordinate system and will reduce the overall size of each footprint polygon.

5. Click OK to run the tool.

Build overviews

Steps:

1. Open the Build Overviews tool.
2. Browse to the mosaic dataset, or click the Mosaic Dataset drop-down arrow to choose the mosaic dataset layer.
3. Click OK to run the tool.

The overviews will take some time to generate. Once completed, the mosaic dataset is ready to use.