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The DXF Editor is the graphical plotting program used in conjunction with RASPLOT to produce standardized NFIP Flood Insurance Study profile tables. In RASPLOT, data is converted from the database files to automatically generate water-surface profiles in the FEMA-approved format, which includes the water-surface profiles, table labels, legend, road crossings, bridges, and culverts. While the program generates most of the needed items for a profile table, there are several details that need to be modified and changed manually. A user will need to know how to use the tools featured in the DXF Editor in order to make these changes.

How To Use the DXF Editor: Modify Tools (Part 4): Fillet & Offset

The MODIFY Tools menu is located on the top main menu bar of the DXF Editor. There are several MODIFY tools that can be used to edit graphical details when creating flood profiles. This issue will explain the Fillet and Offset features under the MODIFY tools menu.

The following descriptions give step-by-step instructions on how to use each tool:

Fillet

Although the Fillet tool is rarely used when modifying water-surface profiles, it is a feature that is available for use within the DXF Editor. The Fillet tool extends a drawing entity (line or arc) to a common intersection point of a second line or arc, maintaining the same slope or arc angle. The second line or arc is automatically trimmed to the nearest intersection point, based upon the mouse location where the second entity is selected (note: only lines and arcs with an eventual intersection point can be filleted; this tool does not work with polylines or non-intersecting entities).

Step-by-Step How-To's:

  1. Select "Fillet" from the Modify dropdown menu.
  2. The Command line will display, "Select Entity 1."
  3. Using the mouse, select the first line or arc you would like to fillet. The Command line will display, "Select Entity 2".
  4. Using the mouse, select the second line or arc you would like to fillet to. Both entities must have at least one common intersecting point.
  5. Entity 1 will automatically be extended to the closest intersection and Entity 2 will be trimmed. The point where you click the mouse for Entity 2 will determine how the DXF Editor will decide to fillet the entities (see Example 1).

Example 1: Fillet 2 Arcs with 4 Different Results

In this example, we will fillet the two arcs.

The Fillet tool will extend and trim two entities at a common intersection point. For example, there are two possible common intersection points of the selected curves:

Selecting "Fillet" from the dropdown menu will prompt you to "Select Entity 1." After selecting Entity 1, the command line will prompt you to "Select Entity 2." After selecting Entity 2, Entity 1 will automatically extend to the closest intersecting point along Entity 2. Entity 2 will be trimmed to the point of intersection on the side furthest away from the selection point of Entity 2.

Four possible results are as follows:

RESULT #1
Entity 1: yellow arc, selected
Entity 2: red arc, selected at point shown
Results: yellow arc filleted to top portion of red arc
RESULT #2
Entity 1: yellow arc, selected
Entity 2: red arc, selected at point shown
Results: yellow arc filleted to bottom portion of red arc
RESULT #3
Entity 1: red arc, selected
Entity 2: yellow arc, selected at point shown
Results: red arc filleted to top portion of yellow arc
RESULT #4
Entity 1: red arc, selected
Entity 2: yellow arc, selected at point shown
Results: yellow arc filleted to bottom portion of red arc

Offset

This tool is used to offset drawing entities by a fixed value.

Step-by-Step How-To's:

  1. Select "Offset" from the Modify dropdown menu.
  2. The Command line will display, "Select Entity to offset."
  3. Using the mouse, select the entity you would like to offset by clicking once.
  4. The Command line will display, "Offset Distance."

    Offset distance can be determined by selecting a distance using the mouse. For example, grid endpoints can be used to offset a water-surface profile by a set distance on a grid.

  5. After clicking two points, the Command line will display, "Side to offset."
  6. Select the side to offset the drawing entity by clicking with the mouse, and the drawing entity will immediately be offset the selected distance.

    Note: Because the Offset tool is a graphical offset, arcs and polylines are offset radially from their center points, and lines are offset perpendicularly from their line angle. Thus, please be aware that this tool does not maintain the precise numerical integrity of water-surface profiles generated by RASPLOT that are offset. Slight variances will occur. Thus, it is not recommended that this tool be used on features that must reflect extremely precise data.

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Last Modified: Tuesday, 26-Jun-2007 11:57:20 EDT