The Simplify tool removes vertices from selected Polylines and Boundary items while preserving the representation of the line's geometry. The tool can be found in the corresponding Tools tab for Polyline and Boundary.

TOOLS for Polyline Tab

TOOLS for Boundary Tab

# The Simplify Tool: Methods and Examples

The Simplify tool works by setting a threshold for how far apart you would like have your vertices in your line. You have two methods for simplifying a survey item.

# 2D Method

## Simplify Contour Lines

A typical use case of needing to simplify a line in 2D is when you receive contour lines that have thousands of vertices. You can quickly simplify these contour lines by selecting one or multiple contour lines, setting your threshold, and clicking on the Simplify tool to reduce (or even greatly reduce) the amount of vertices on all the lines.

As shown in the images above, you can retain the shape of the contour line with far fewer vertices and still have a clean model of the terrain.

To quickly simplify one or multiple contour lines, follow these steps:

1. Select the line, or select multiple lines, and go to the TOOLS tab.
1. To see the vertices of the line, you can go to the TOOLS tab and click on Edit Vertex.
2. In the Simplify section, set the desired Threshold.
1. In this example we used 0.50 m².
3. Click Simplify.

# 3D Method

## Simplify a 3D Polyline

You can simplify the 3D polyline while maintaining the form of the line.

1. Select the 3D Polyline.
1. To see the vertices of the line, you can go to the TOOLS tab and click on Edit Vertex
1. In this example we used 0.20 m².
3. Click Simplify.

The polyline preserves the slope as much as possible with fewer vertices while maintaining the form and path of the line.

## Simplify a Boundary

Regardless of why you are simplifying your boundary, you use the same process when utilizing the Simplify tool:

1. Select the boundary.
1. To see the vertices of the line, you can go to the TOOLS tab and click on Edit Vertex.
1. In this example we used 20.00 m².
3. Click Simplify.

The boundary retains its shape with fewer vertices without losing its shape along the boundary line.

Here are examples of three situations where you may need to simplify your boundary:

• When you need to quickly expand or shrink your boundary by editing corner vertices.
• Simplify a complex boundary to increase performance and usability.
• Avoid small triangles on the border of your TIN by keeping the density of your boundary vertices similar to the survey points.

### Edit the Boundary Shape

When you need to quickly update your boundary shape by adding or removing parts of the project area you need to work within, your boundary may have too many vertices to make a quick edit.

As shown in the images below, it is much easier to edit a boundary with fewer vertices. The Simplify tool will make this process much faster. Use Simplify to quickly edit your boundary, then use the Densify tool to add vertices back onto the boundary line if you want to match the boundary closely with the Elevation Terrain.

### Simplify a Boundary for Performance and Usability

A boundary with fewer vertices means a faster response time. The density of a boundary's vertices can influence Virtual Surveyor's processing performance. In essence, the simpler a boundary, the better the software will perform. You can use the Simplify tool to quickly remove vertices from a boundary and improve processing times.

### Remove Vertices from Boundary to Reduce Excess Triangles

If a boundary has too many vertices due to overly densifying or simply from having a boundary with too many points, the Simplify tool makes it fast to simplify the boundary by removing vertices to better match the overall density of the surveyed points and lines.

# Setting the Threshold

How the threshold works is a concept that is fairly difficult to explain, but is at the very least simple to use. So to help you move on with your work, we'll give you a quick definition and straight-forward explanation.

The Threshold setting for the Simplify tool is a criterium used to change the form of an area between vertices on a line, i.e., the area threshold or tolerance that allows you to change the form of a line when you drop a vertex. When you set your threshold value to a number that is lower than the area between points on a line, you get fewer vertices on your line.

As a basic principle to help you set the desired threshold: a lower value of threshold removes fewer vertices from your line, while a higher value  means you remove more vertices from your line. It may take some trial and error by starting at a chosen value, then gradually increasing or decreasing the value until you get the results you are looking for.

# Tips & Tricks

• It can be very difficult to know what threshold value to use up front; the easiest process for setting the proper threshold is through trial and error:
• Simplify your selected line, then undo the action and keep changing the parameter until you get the desired result.
• You can always use the Edit Vertex tool to further remove or add vertices where you need them on your simplified line.