Measure

The Measure map tool is used to measure distance between points or objects on the map or the area of a polygon delineated by the user. Under the Map Tools icon, click  Measure, then select Distance or Area. When measurements are complete, use the Clear All Graphics from Map icon to clear the measurement graphics from the map and close the Measure Tool pop-up box.

Distance

When measuring Distance, click Distance then click on the map at the start point of the measurement. A Measure Tool pop-up box will open displaying the categories of distance and the starting elevation, with units displayed as those selected in the Settings tab of the Map pane. Move the cursor to the end point and click again to display the distance covered and the elevation value of the ending point. To measure multiple segments, click again on the next end point. The distance total updates with the total distance covered over all points and the ending elevation is also displayed in sequence.

Area

To measure Area, click Area, then click on the map to define the start point of the area polygon. Move the cursor to the location of the next corner or vertex of the area-defining polygon and click again, continue to define vertices of the polygon area of interest. When complete, double click to release the cursor. The total area of the polygon is given in the Measure Tool pop-up box in units previously selected under the Settings tab of the map.

Geoprocessing

Numerous geoprocessing functions are available in the eRAMS GIS toolbox including tools for working with feature classes, performing proximity operations, obtaining zonal stats, and working with rasters. Click on the Map Tools icon to open the toolbox and select Geoprocessing. Click on the toolset pertaining to the set of operations of interest.

Geostatistics: Spatial Interpolation

The Geostatistics Spatial Interpolation tool allows you to estimate the values of properties at unsampled sites within the area covered by existing observations. Point values are interpolated to a new raster surface.

Select Geostatistics from the GIS toolbox and then click on Geostatistics. Click on Spatial Interpolation. In the Point Layer: drop-down menu select the layer of interest. In the Attribute: drop-down menu select the attribute to be used for interpolation.

Next, select one of the three interpolation methods offered: Kriging, IDW, or Nearest Neighbor.

Kriging

Kriging is an advanced procedure that produces an estimated statistical surface from points using z-values to create the surface. Semivariogram properties can be controlled through specification of Nugget:, Range: and Sill: values which can be input by checking the Specify Advanced Options box below the Output Cell Size: box.

Inverse Distance Weighting

IDW is a method that estimates interpolated values through averaging the values of sample data points near the cell of interest. Greater weight is given to values nearer the cell than those further away. Advanced Options may be used by checking the box below the Output Cell Size: box. These options include Power:, Smoothing:, Max points:, Radius 1:, Radius 2:, Angle:, and assignment of a Nodata: value.

Nearest Neighbor

Nearest Neighbor interpolation uses the value of the closest point to assign a value to a cell.  Advanced Options may be used by checking the box below the Output Cell Size: box. These options include Radius 1:, Radius 2:, Angle:, and Nodata.

Extract Data

The Extract Data toolset allows the user to select and extract data of interest for subsequent analysis. Climate, surface water, groundwater, hydrographic, crop, and soil data are available from a variety of public sources.

Digitize & Edit

Select the Digitize/Edit tool edit feature layers through heads-up-digitizing operations.  To Edit a layer: use the drop-down menu to select the layer of interest. Only vector layers can be modified with this tool. Make sure the layer is visible or active. The geometry of the selected layer controls which editing functions are available.

Add

To add new shapes:

Polygons

Add a Polygon allows delineation of a new polygon on the map by clicking and moving the cursor to the next vertex and clicking, then double-clicking when done to define the shape. When the shape is defined, a pop-up dialog box asks for the name of the new shape. Enter the name of the new field: by clicking in the box and typing it in. When done click Ok. The polygon is appended to the end of the attribute table of the selected file through creation of a new gid with the name included in the name attribute field.

Circle

Add a Circle allows delineation of a new polygon circle on the map by clicking, holding down the mouse button and dragging the cursor to define the size of the circle. A pop-up dialog box asks for the name of the new shape. Enter the name of the new field: by clicking in the box and typing it in. When done click Ok. The circle is appended to the end of the attribute table of the selected file through creation of a new gid with the name included in the name attribute field.

Lines

Add a Line allows delineation of a new line on the map by clicking and moving the cursor to the next vertex and clicking, then double-clicking when done. When the line is defined, a pop-up dialog box asks for the name of the new line. Enter the name of the new field: by clicking in the box and typing it in. When done click Ok. The line is appended to the end of the attribute table of the selected file through creation of a new gid with the name included in the name attribute field.

Points

Add a Point allows delineation of a new polygon on the map by clicking on the map. A pop-up dialog box asks for the name of the new shape. Enter the name of the new field: by clicking in the box and typing it in. When done click Ok. The point is appended to the end of the attribute table of the selected file through creation of a new gid with the name included in the name attribute field.

Edit

To edit features, the layer of interest should be active and selected in the Edit layer: drop-down menu. Set the Snapping tolerances in the Snapping box by selecting the Target file from the drop-down menu and setting a tolerance in the Tolerance: box in meters. Nodes, vertices, and edges can be snapped to by selecting the appropriate checkbox.

Click on Select Features for Editing, then click on the feature to edit. The feature boundary or line should become highlighted, and any vertices will also become highlighted. For points, the point will be highlighted.

Options for heads-up digitizing and editing include:

• Edit Vertices, this allows movement of vertices to new locations by clicking and dragging on the vertex of interest.
• Save Feature Edits, click on this to save any edits.
• Undo Feature Edits, returns features to the previously saved state.
• Delete Selected, click on this to remove the feature