Example 1: Calculating the distance between markers

     This example is also available on YouTube.

Introduction

In this example, we will measure the distance between one position in an image to a list of markers.

Steps to do

Develop your network

Add the following modules and connect them as shown.

We changed the names of the modules SoView2DMarkerEditor and XMarkerLIstContainer, to distinguish these modules from two similar modules we will add later on. Open the panel of SoView2DMarkerEditor and select the tab Drawing. Now chose the Color red.

As a next step, add two more modules: SoView2DMarkerEditor and XMarkerLIstContainer.

Change their names and the marker color to green and connect them as shown. We also like to change the mouse button you need to press, in order to create a marker. This allows to place both types of markers, the red ones and the green ones. In order to do this, open the panel of GreenMarker. Under Buttons you can adjust, which button needs to be pressed in order to place a marker. Select the Button2 (the middle button of your mouse ) instead of Button1 (the left mouse button ).

In addition to that, we like to allow only one green marker to be present. If we place a new marker, the old marker should vanish. For this, select the Max Size to be one and select Overflow Mode: Remove All.

Create markers of different type

Now we can place as many red markers as we like, using the left mouse button and one green marker using the middle mouse button .

Calculate the distance between markers

We like to calculate the minimum and maximum distance of the green marker to all the red markers. In order to do this, add the module DistanceFromXMarkerList and connect it to RedMarkerList. Open the panels of DistanceFromXMarkerList and GreenMarkerList. Now, draw a parameter connection from the coordinates of the green marker, which are stored in the field Current Item -> Position in the panel of GreenMarkerList to the field Position of DistanceFromXMarkerList. You can now press Calculate Distance in the panel of DistanceFromXMatkerList to see the result, meaning the distance of the green marker to all the red markers in the panel of DistanceFromXMarkerList.

Automation of distance calculation

To automatically update the calculation when placing a new marker, we need to tell the module DistanceFromXMarkerList when a new green marker is placed. Open the panels of DistanceFromXMarkerList and GreenMarker and draw a parameter connection from the field Currently busy in the panel of GreenMarker to Calculate Distance in the panel of DistanceFromXMarkerList. If you now place a new green marker, the distance from the new green marker to all red markers is automatically calculated.

Summary

• Markers can be created using SoView2DMarkerEditor
• Markers can be stored and managed using XMarkerListContainer
• The distance between markers can be calculated using DistanceFromXMarkerList

   Download .mlab file here.