Creating a Steep Slopes Analysis with InRoads’ View Color Coded Slopes Tool

If you recall, the previous blog post introduced our target assignment. We will use InRoads View Color Coded Slopes tool to generate a Steep Slopes Analysis as required to meet certain jurisdictional requirements. We frequently need to develop plans that identify areas with steep slopes. Hopefully, when you have a series of regular workflows, you create and save preferences to streamline the process. The slope ranges our local regulations require are: slopes less than 15%, slopes from 15% to 25% and slopes greater than 25%. A quick internet search indicates that these ranges appear to be fairly common, but if you have a need for different slopes, the basic concepts can be easily modified.

The majority of the efforts required to repeat this workflow occur on the Color Table tab of the View Color Coded Slopes tool. The following image shows the main settings needed for this task. At our office, we have a client supplied standard/default color table which can be used unmodified for this task. On occasion, I have found it beneficial to create a custom color table, but since we are only going to use three slope ranges, selecting colors already within our standard color table is not difficult.

In order to edit the color ranges, you must visit the Main tab and change the Color mode from Automatic to Custom.

The tool uses three columns of settings: a From Slope, a To Slope and a Color. The InRoads tool starts the lowest range with a From Slope of 0%. Using a custom set of three ranges, we set all slopes less than 15% to plot using color 10, an on-screen white that plots white. The agencies are not interested in slopes that are less than 15%, so this technique results in output that seems to ignore the lowest range.

The 15% to 25% color was set to a yellow that also displays and plots yellow. The same approach was used for the greater than 25% range, being set to a “display and plot” red. Once the command has been run and all of the slope shapes are plotted, we used the Power Selector to select and delete all shapes drawn with color 10. Since our color 10 plots white, this is not critical, but does reduce file size substantially. I should point out that in our client supplied workspace, the default color table uses the bottom row and half of the row above for color WYSIWYG output. All other colors plot 100% black, with the lone exception of the previously used color 10. To bring this technique into other workspaces, select colors based upon how they display and plot on the target workspace.

The tool can be used to generate a list of ranges as a starting point. The Edit, Insert and Delete buttons on the right side of the tab can be used to modify them once they are created. This is only possible when the Color Mode, on the Main tab, has been changed to Custom.

One of the real strengths of InRoads is the Preferences buttons found on most dialog boxes. These allow you to save a group of settings for tasks that need to be repeated on multiple projects. When saving Preferences, try to follow some sort of naming convention. While not every tool has a Preferences button, I believe they should. The nuances of Preferences will have to wait for another post.

As defined, our output lends itself to color plots. To generate a similar display for monochromatic reproduction, it may be necessary to select different colors. This type of display is frequently used with a contour display. When printing for non-color output, the steep slope colors must have sufficient contrast from the contours, as well as any other displayed data. Testing may also be in order to confirm that the selected contrast is still sufficient after copies are made from hardcopy. There have been issues in the past, where agencies complained about the lack of contrast. Frequently, this was aggravated by the practice of making copies of copies.

The following image shows an area of the site created with this workflow.

I hope this gets you looking for other areas where you are not taking advantage of the tools already at your disposal.

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