3D Analyst Tools ArcToolbox

Aspect, Contour Tools

Aspect

How to use Aspect Tool in ArcToolbox ArcMap ArcGIS ??

Aspect Tool

Aspect Tool, Raster Surface Toolset, 3D Analyst Toolbox

Aspect

Derives the aspect from each cell of a raster surface.

The aspect identifies the compass direction that the downhill slope faces for each location.

1. Input raster

The input surface raster.

2. Output raster

The output aspect raster.

It will be floating-point type.

3. Method (optional)

Determines whether to calculate the aspect based on a planar (flat earth) or a geodesic (ellipsoid) method.

· PLANAR—The calculation will be performed on a projected flat plane using a 2D Cartesian coordinate system. This is the default method.

· GEODESIC—The calculation will be performed in a 3D Cartesian coordinate system by considering the shape of earth as an ellipsoid.

The planar method is appropriate to use on local areas in a projection that maintains correct distance and area. It is suitable for analysis that cover areas such cities, counties, or smaller states in area. The geodesic method produces a more accurate result, at the potential cost of an increase in processing time.

4. Z unit (optional)

Linear unit of vertical z-values.

It is defined by a vertical coordinate system if it exists. If a vertical coordinate system does not exist, the z-unit should be defined from the unit list to ensure correct geodesic computation. By default, Meter would be applied.

· INCH—For inches (U.S.)

· FOOT—For feet

· YARD—For yards (U.S.)

· MILE_US—For miles (U.S.)

· NAUTICAL_MILE—For nautical miles

· MILLIMETER—For millimeters

· CENTIMETER—For centimeters

· METER—For meters

· KILOMETER—For kilometers

· DECIMETER —For decimeters

Contour

How to use Contour Tool in ArcToolbox ArcMap ArcGIS ??

Contour Tool

Contour Tool, Raster Surface Toolset, 3D Analyst Toolbox:

Contour

Creates a feature class of contours from a raster surface.

1. Input raster

The input surface raster.

2. Output feature class

The output contour features.

3. Contour interval

The interval, or distance, between contour lines.

This can be any positive number.

4. Base contour (optional)

The base contour value.

Contours are generated above and below this value as needed to cover the entire value range of the input raster. The default is zero.

5. Z factor (optional)

The unit conversion factor used when generating contours. The default value is 1.

The contour lines are generated based on the z-values in the input raster, which are often measured in units of meters or feet. With the default value of 1, the contours will be in the same units as the z-values of the input raster. To create contours in a different unit than that of the z-values, set an appropriate value for the z-factor. Note that it is not necessary to have the ground x,y and surface z-units be consistent for this tool.

For example, if the elevation values in your input raster are in feet, but you want the contours to be generated based on units of meters, set the z-factor to 0.3048 (since 1 foot = 0.3048 meter).

For another example, consider an input raster in WGS_84 geographic coordinates and elevation units of meters for which you want to generate contour lines every 100 feet with a base of 50 feet (so the contours will be 50 ft, 150 ft, 250 ft, and so on). To do this, set the Contour interval to 100, the Base contour to 50, and the Z factor to 3.2808 (since 1 meter = 3.2808 feet).

6. Contour type (optional)

The type of output. The output can represent the contours as either lines or polygons. For polygons, there are several options to choose from.

· CONTOUR—Polyline feature class of contours (isolines). This is the default.

· CONTOUR_POLYGON—Polygon feature class of filled contours.

· CONTOUR_SHELL—Polygon feature class where the upper bound of the polygon increases cumulatively by the interval value. The lower bound remains constant at the raster minimum.

· CONTOUR_SHELL_UP—Polygon feature class where the lower bound of the polygon increases cumulatively, from the raster minimum, by the interval value, and where the upper bound remains constant at the raster maximum.

7. Maximum vertices per feature (optional)

Specifies a vertex limit when subdividing a feature. This should only be used when output features contain a very large number of vertices (many millions).

This parameter is intended as a way to subdivide extremely large features that can cause issues later on, for example, when storing, analyzing, or drawing the features.

If left empty, the output features will not be split. The default is empty.