ArcGIS Engine Developer Guide

BUILDING A COMMAND-LINE C++ APPLICATION
Rather than walk through this scenario, you can
get the completed application from the samples
installation location. The sample is installed as
part of the ArcGIS developer samples.
The ArcGIS developer samples are not included
in the typical installation of the ArcGIS Engine
Developer Kit. If you do not have them installed,
rerun the Developer Kit Install wizard, click
Custom or Modify, and click the samples feature
under Software Developer Kit.
Although this scenario steps you through C++
development, solution code is also available in
other programming languages, including C#, Java,
Visual Basic 6, Visual Basic .NET, and Visual
C++.
For a more in-depth explanation of slope, see
the Burrough and McDonnell reference listed in
the 'Additional resources' section at the end of
this scenario.
This scenario is designed to introduce the ArcGIS Engine C++ API for crossplatform
applications. To get the most out of this scenario, you should understand
basic C/C++ programming concepts such as the preprocessor, functions,
and memory management. Some familiarity with ArcObjects will also be helpful,
although not required. Although this scenario does require conceptual knowledge
of the C++ language, it does not require a lot of programming experience. The
code used in this example provides an easy entry point to learn about the C++
API to ArcGIS Engine on a small and simple scale.
The purpose of this scenario is not to teach how to set up a C++ environment or
how to compile on each supported operating system. Throughout this scenario it
is assumed that you have a functional C++ environment and know how to
compile a C++ program in that environment. What this scenario does provide is
the steps to take and the code to write to create a command-line application that
computes the slope of a given digital elevation model.
You can find this sample in:
\DeveloperKit\samples\Developer_Guide_Scenarios\
Computing_the_Slope_of_a_Raster_DatasetCpp.zip
PROJECT DESCRIPTION
This scenario covers some aspects of the ArcGIS Engine C++ API. The goal of
the RasterSlope scenario is to create a standalone command-line application with
the ArcGIS C++ API. The application will take as input a digital elevation model
(DEM) and will build and persist the slope map raster dataset. Once you have
completed this scenario, you will understand the techniques required to work
with the ArcGIS Engine C++ API, including using the Spatial extension. In
particular, the scenario covers the following techniques:
• Programming with the ArcGIS Engine C++ developer kit in a standard text
editor.
• Parsing command-line arguments.
• Enabling extensions—in particular, the Spatial extension.
• Performing the calculation of slope on a raster dataset.
• Persisting the resultant raster dataset.
• Deploying the application on all platforms supported by the ArcGIS Engine
C++ API.
CONCEPTS
Slope datasets are often used as inputs in physical process models. Slope is commonly
expressed in degrees or as a percentage. In the slope calculation a parameter
(zFactor) can specify the number of ground x,y units in one z unit. This
allows you to create a slope dataset with different z units from the input surface.
To build the slope dataset, you will use the RasterSurfaceOp class and the
ISurfaceOp interface it implements. You will also use the Raster class and the
IRasterBandCollection interface it implements to persist the resulting raster dataset.
The role of the software is to calculate the slope of a given raster dataset. The
Chapter 6 • Developer scenarios • 427