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Using 3dMapper for Idaho Soil Survey Analysis

The 3dMapper program is designed to look at the slope characteristics of a landscape using digital elevation data.  It is possible to "drape" an orthophoto over a wire frame model of the landscape to depict actual surface topography.  It is also possible to place existing soil lines over the landscape model.  This Web site will describe the basic procedures for getting data into 3dMapper and for making initial use of the data.

Note: This tutorial was written in 2003 and applies to Version 2 of the free 3dMapper program and utilizes commands from ArcGIS 8.3. There are differences between these and subsequent versions.   It also references obtaining soil survey data from "the National NRCS SSURGO Download Site" which should now be "the NRCS Soil Data Mart". A few other subtle differences might be present as technology has surged ahead since 2003! 

For more information, please visit the University of Wisconsin's 3D Mapper and SoLIM project web sites.



TABLE OF CONTENTS

Obtaining the Software - Page 1
Obtaining and Preparing the Data - Page 1
Starting the 3dMapper Program - Page 1
Importing the Data - Page 1  
Opening an Existing 3dMapper File - Page 1
Using 3dMapper - Page 1
Adding a North Arrow - Page 1
Adding Slope Classes - Page 1
Adding Aspect Classes - Page 2
Looking at Landscape Curvature- Page 2
Adding Existing Digital Soil Lines- Page 2
Data at the Cursor Location - Page 2
Plotting a Transect - Page 2
Adding Contour Lines - Page 2
Printing Maps - Page 2
Other Features - Page 2

Obtaining the Software

Download the 3dMapper software
Download the 3dMapper Help File

Table of Contents

Obtaining and Preparing the Data

Note:  All of the data used must be in the exact same projection, including datum, or it will not line up in the program!

  1. Obtaining digital elevation data

Digital elevaton model (DEM) data is available from the Idaho Department of Lands Interactive Data Server by selecting "Level 2 DEM" under the "Available Data" heading.  Once the appropriate DEM has been downloaded, it must be processed in ArcInfo using the following structure:

Arc:  DEMLATTICE [downloaded DEM] [new file name] USGS 1
Arc:  PROJECT GRID ... (if needed)
Arc:  GRIDASCII [new file name] [ASCII file name with an .asc extension]

Example
Arc:  DEMLATTICE f1436.dem robiedem USGS 1
Arc:  GRIDASCII robiedem robiedem.asc

  1. Obtaining digital orthophotography

Digital orthoimagery needs to be obtained through the State Office.  A variety of file formats can be used but not the compressed files in the MrSID format.  Some is in full quad format and other is in quarter quad format.  Once the appropriate orthoimagery has been obtained, it must be processed in ArcInfo using the following structure:

Arc:  IMAGEGRID [imagery file name] [GRID file name]
Arc:  PROJECT GRID ... (if needed)
Arc:  GRIDASCII [GRID file name] [ASCII file name with .asc extension]

Example
Arc:  IMAGEGRID f1oq4316.bil robiedoq
Arc:  GRIDASCII robiedoq robiedoq.asc

  1. Obtaining digital soil survey data

Digital soil survey data can be obtained over the Internet at the National NRCS SSURGO Download Site or through the State Office.  Once the selected soil survey data has been projected and aligned with the imagery and the elevation data it must be processed in ArcInfo using the following structure:

Arc:  COPY [soils coverage] [new soils coverage] SINGLE
Arc:  CLEAN [new soils coverage]
Arc:  PROJECT COVER ... (if needed)
Arc:  UNGENERATE LINE [new soils coverage] [ASCII file name with .arc extension]

Example
Arc:  COPY id610_a foothills SINGLE
Arc:  CLEAN foothills
Arc:  UNGENERATE LINE foothills foothills.arc

As a result of the three above steps, there should now be three ASCII files, all with the same georeferencing; one for imagery, one for elevation, and one for soils.  These three files will be imported into the 3dMapper program as described in the next step.

Table of Contents

Obtaining and Preparing the Data

Starting the 3d Mapper Program

Using Windows Explorer or My Computer, go to the directory where the program resides.

3-D Mapper Directory
 

Double-click on the file name "3dmapper0101" and the screen below will appear.

3-D Mapper
 

Table of Contents

Importing the Data

3dMapper merges the imagery and the elevation data through the following steps:

 

  1. On the 3dMapper menu bar, choose File / Import Ascii / Base Dem/Photo

3-D Mapper Menu Bar
 

  1. The first screen after this prompts for the location of the ASCII DEM file prepared in Step 1 of Obtaining and Preparing the Data above.

Open ascii DEM file
 

  1. The next screen prompts for the location of the ASCII imagery file prepared in Step 2 of Obtaining and Preparing the Data above.

Open ascii Photo File
 

  1. The next screen prompts for a file name to write the merged data set to.  Be sure and specify a ".3dm" extension since one is not added automatically.

3-D Mapper DEM Photo pair
 

  1. The next two screens establish the horizontal and vertical units.  Assume "METERS" if unsure and type in that word for each of the screens.

Horizontal Grid Units
 

  1. The last screen shows the progress of the digital processing.  The top red arrow below shows the total number of rows for processing.  Progress towards the end can be followed by watching the numbers at the lower second arrow.

3-D Mapper Digital Processing
 

  1. When all processes have finished (5-10 minutes), a new window entitles "FullImage" will pop up with the merged data set displayed.

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Opening an Existing 3dMapper File

If you just completed the previous steps then you are at the Full Image viewing window and can skip this section.  This is where you would start if all the pre-processing was done and you were just trying to open up an existing file.

If you are lucky enough to have a kind state office, then you may already be at this point and ready to start!

  1. On the 3dMapper menu bar, choose File / Open Binary / Base Dem/Photo

3-D Mapper Menu Bar
 

  1. Assuming the files were named correctly in Step 4 of Importing the Data then navigate to the correct directory and select the appropriate ".3dm" file (the merged DOQ and DEM file).

3-D Mapper DEM Photo File
 

  1. When all processes have finished (10-15 seconds), a new window entitled "FullImage" will pop up with the merged data set displayed.
     

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Using 3dMapper

With the FullView displayed, the next step is to define a smaller, or equal, viewing area.  The larger the local view, the longer it will take to recalculate the slope information and redraw the screen.  Define a local view by selecting the Define Local View button.

3-D Mapper Define Local View
 

 

 

The local view is selected by placing the cursor on the FullView screen, holding down the left mouse button and sizing an elastic box.  When the local view window pops up it has many items written around the screen.  The following is a description of each of those items.

Fulll View 14.0m cells
 

The top four items (1-4) change as the screen is resized, zoomed into and out of, and altered in other ways.

  1. Scale - This shows the cell size and the width of the display in cells.  Scale is randomly set but can be changed.
  2. Vertical exaggeration - A value of 1.0 is no exaggeration but sometimes exaggeration helps to display features.
  3. Horizontal tilt - The number of degrees off the ground for the view.  A value of 90 means directly overhead.
  4. Scale - This is the map scale of the display image.

The bottom four items (5-8) are there as reminders for ways to manipulate the display.

  1. View Change - Dragging the left mouse button rotates the view.
  2. Exaggeration Change - Dragging the right mouse button changes the vertical exaggeration.
  3. Zoom - Holding down the Shift key and dragging the left mouse button zooms in on the display.
  4. Pan - Holding down the Alt key and dragging the left mouse button pans around on the display.

Example

After manipulating the image with the commands on the bottom of the screen, the image below has the following properties:

  • A resolution of 8 meter cells
  • A 2.5 vertical exaggeration factor
  • A tilt of the block image by 21 degrees
  • A screen image scale of 1:18,696

Full View 8.0m cell
 

Table of Contents

Adding a North Arrow

Add a colored north arrow to the Local View by selecting Options / North Arrow / Scale.  It will stay displayed until clicked off.

3-D Mapper North Arrow
 

Table of Contents

Adding Slope Classes

First, click on the Slope option under Coverages.  Then click the Apply button and the slope classes will draw on the Local View and a new window will pop up showing the legend classes.

3-D Mapper Slope
 

After some calculations, the Local View will reappear with the following default slope classes:

Slope Classes and Colors
 

The classed map ranges (in % slope) can be changed simply by typing in new values on the left side of the above screen.  An unclassed slope map can be generated by changing one or both of the ends of the color ramp on the right side of the above screen.

The default slope map classifies all cells of data on the image.  This is sometimes confusing and a more generalized map is needed.  To do this, select Options / Slope Neighborhood.

3-D Mapper Slope Neighborhood
 

The following dialogue box will appear.  The greater the smoothing distance, the more cells will be averaged.  Experiment until the desired effect is obtained.

Slope Neighborhood Size
 

The next two images below represent before and after slope smoothing.  The first is before smoothing the second is after a smoothing of 200 meters.

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