﻿ Simplify Art

# Simplify Art

Simplify Art allows for the simplification or generalization of vector line and area data. Use either the popular Douglas-Peucker or Visvalingam-Whyatt method for removing nodes and vertices during simplification.

Simplify Art is used to reduce the number of points required to represent a vector-encoded line where lines are approximated by a stream of X-Y coordinates. The operation can be used on Line or Area MAP layers and removes nodes based upon a proximity value in either Page Units or Map Units. The list of map units depends on the MAP View coordinate system—e.g. angular units (page units, degrees, etc) for geodetic coordinate systems; linear units (such as metre, feet) for projected coordinate systems.

Using Simplify Art

To use Simplify Art, select the lines on a Line layer or areas on an Area layer, then click the Simplify Art button on the MAPublisher toolbar or from the menu Object > MAPublisher > Simplify Art.

The Douglas-Peucker method takes the proximity value and iterates through the line vertices to determine the points that fall within the specified proximity distance off the line and removes those vertices. Once all vertices are determined to be greater than the proximity value, the line processing ends. A smaller proximity value will usually result in a fewer number of nodes being removed. The Visvalingam-Whyatt method is an area based algorithm which eliminates points based on their effective area. By iterating through points of lines and areas, it calculates and removes the point with the least effective area.

The Proximity value or simplification tolerance is based on the vertical difference between the begin/end line and points off a line, not the distance between anchor points on the line.  Enter a Proximity value in Page Units or Map Units by making a selection from the Units drop-down list. Page Units are the units of the current document. Enter a proximity value in the unit specified by typing a value or by using the arrows.

The Fault Tolerance setting allows you to control how much tolerance is allowed to accommodate for a small amount of positional error between shared edges in the topology. Your results may vary depending on how accurate your data may be.

Click the Preview button to see the simplification result before committing to it. The Vertex Count shows how many vertices are in the simplified result (and calculates a percentage of overall simplification). Adjust the proximity as necessary in order to achieve the desired results particular to the scale and coverage area. Click OK to complete the simplify operation.

Results

All selected lines or areas are simplified according to the settings. Simplified lines or areas will not be simplified again unless the tolerance value is increased. For example, if a line has been simplified with a proximity of 1.5 km, then it will not be simplified again until the tolerance is set to a value larger than 1.5 km.

In practice, it means that simplified lines can be selected again with non-simplified lines to run the operation again. When Simplify Art is run, only the new lines will be simplified (unless the proximity value is increased).

It is a good idea to perform Simplify Art on artwork before exporting to a web map. This will reduce the file size and improve performance and loading times.

Simplify Art will simplify stretches of a path that are non-bezier even if bezier components exist on the path. However, it will never remove bezier points.

Bezier curves cannot be simplified using Simplify Art. To smooth the appearance of paths containing bezier curves (achieve a non-bezier approximation), use the Adobe Illustrator Simplify tool (menu Object > Path > Simplify) and set the angle to 0 degrees and enable the Straight Lines option. If the result is not acceptable, you may need to add anchor points to give it enough fidelity to make a non-bezier line without damaging the path's detail. After that, you can run Simplify Lines and remove any unnecessary anchor points.