[027] Global Mapper - Spatial Operations 03: Transforms

Today is our third session on Spatial Operations, focusing on Transforms. What makes this feature different from the previous two is that it doesn't just select, split, or delete; instead, it targets a single layer and creates new geometries based on the elements contained within that layer.

"Before we begin, if you missed the previous session, check it out here:"

026] Global Mapper - Spatial Operations 02: Understanding Predicates

Let's get started.

First, open the file from the previous session. Since this content doesn't require extensive explanation, we'll go through it quickly.

[img 1 : Global Mapper Control Center showing the layer list including Area01]

Activate the Area01 layer.

Now, let's examine the menu.

[img 2 : Spatial Operations dialog box focusing on the Transforms tab]

Spatial Transforms: Methods for Generating New Geometries

• MBR (Minimum Bounding Rectangle): Generates the minimum bounding rectangle for the selected geometry group. It creates the smallest possible rectangle that encompasses all features.
• Centroid: Calculates the center point of Area or Line features. It returns the center of mass for area features or the geometric center for line features.
• Center: Calculates the center point of the Minimum Bounding Rectangle (MBR) of the selected geometry group. Unlike the Centroid, it calculates the center based on the MBR.
• Circle: Generates a minimum enclosing circle based on the center point of the selected geometry group. It creates the smallest circle that contains all features.
• Buffer: Creates a buffer area around the selected features at a specific distance. You can specify the distance and units (e.g., meters, feet).
• Convex Hull: Generates a convex polygon for the selected geometry group. It is the smallest convex polygon that contains all features.
• Concave Hull: Generates a concave polygon for the selected geometry group. It creates a more detailed boundary polygon that follows the shape of the features more closely.
• Dissolve: Merges features with the same attribute values into a single feature. It creates new areas by grouping them based on attributes.

Grouping: Methods for Grouping the Resulting Output

• No Grouping: No grouping is performed. Each element is processed independently. For example, every element will individually generate its own Convex Hull, Centroid, or Buffer.
• Group by Attribute: Groups elements with the same attribute value for processing. You must select the attribute to be used for grouping.
• Group All: Groups all selected elements into a single group for processing. It considers all elements in the group to create a single result (e.g., one Convex Hull, one Buffer, etc.).

Buffer Width: Defines the interval for the buffer. This is used when performing the Buffer function.

Hull Smoothing: Used when applying Convex or Concave Hull. It indicates the degree of smoothness for the boundary line.

Let's start by looking at MBR.

[img 3 : Configuring MBR settings in the Spatial Operations window]

Set it up as shown above and click Run.

The result is as follows:

[img 5 : Resulting MBR layer shown as a rectangle surrounding Area01]

A rectangle surrounding Area01 has been created.

Next is the Centroid.

[img 6 : Centroid transform settings in the Spatial Operations dialog]

The result is:

[img 7 : A point created at the center of mass or geometric center of the shape]

A point has appeared at the center of mass or geometric center.

Next, let's look at Center.

[img 8 : Center transform settings in the Spatial Operations dialog]

The result:

[img 9 : Center point created based on the MBR]

The point has been created, though its position is slightly different. Let's turn on both the Centroid and Center layers to compare them.

[img 10 : Comparison between Center and Centroid points]

The red point was created by the Center function, and the orange point was created by the Centroid function.

As mentioned in the menu description, the Center is the center point of the MBR, while the Centroid is the center of mass. This is why there is a slight difference between the two.

Next is the Circle function.

[img 11 : Circle transform settings with a 10m radius]

The Circle function draws a concentric circle based on the center of mass or geometric center of the elements in the layer. In other words, it draws a circle centered on the point created by the Centroid function.

The result:

[img 12 : Resulting circle layer centered on the centroid point]

I activated the Centroid layer to verify if it aligns with the center point of the Circle.

Next is the Buffer function.

You can understand this as a feature used when you need to draw a radius or boundary based on the edge of a zone.

[img 13 : Buffer transform settings with a 10m width and Dissolve results checked]

I set it to draw a buffer surrounding Area01 with a 10-meter interval from the boundary.

The result:

[img 14 : Final buffer result shown as a 10m offset from the original Area01 shape]

Since Transforms only targets a single layer, there isn't much to worry about. It's quite simple, isn't it?

We've taken a general look at the Transforms feature.

If you have some extra time, try practicing the remaining functions and applying them to other layers as well.

That leaves us with Scripting. However, I haven't personally used this part yet, so I can't teach it to you. You can press the F1 key in the Spatial Operations screen to open the help window and look into Spatial Operations Scripting. For those who require advanced calculations, I encourage you to study it on your own.

That's it for today!

"In the next session, we'll dive deeper into more advanced features. Stay tuned!"

028] Global Mapper - Moving Attributes: Copy Attributes Between Overlapping or Nearby Features