Drawing point symbols

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Creating your own symbology

Cadplan's Vertexsymbol plugin allows to add point symbols to vertex on an OpenJUMP layer. It allows to use external raster, SVG and WKT images as symbology. SVG and WKT seems very usefull since they can be scaled (using plugin options) and rotated according to attribute values. Tis tutorial will help the users to customize any vector drawing to WKT files and to use it as a point symbol.

Basic rules

The actions require the following 4 steps:

  1. Convert the souce vector image you would like to have as symbol to a DXF format
  2. Load the DXF souce file in OpenJUMP and warp it to the (o o) origen coordinate, scaling to the right dimension. Save the file to WKT format
  3. Load the WKT source file with a text editor and add dimension and line width following Cadplan specification, Save back to WKT format
  4. Put the WKT file in the OpenJUMP/LIB/EXT/VERTEXSYMBOL folder to use tit as symbol

Step 1

Many drawing software allows to convert a vector drawing to DXF format. I use ZonerDRAW 3, the free version of software, to convert drawing, it can export also text to DXF curve which is very useful if you want to convert any TTF font to a DXF file. Remember not to use complicated symbology, even if thid method works quite fine. By the time that the drawing is exported to DXF it may not have the right coordinate position and the dimension to use as symbol. So save your file to SOURCE.DXF and go to step 2

Step 2

This part requires extra attention. You have to:

  • georeference your drawing so that its centre conrespond to the (0 0) coordinates in OpenJUMP
  • Rescale it so that it fits in a 20x20 cell square in OpenJUMP

To help you on this procedure, I have prepared a special file (http://jump-pilot.sourceforge.net/download/Resources/grid.zip grid.wkt) that shows a grid. This grid makes the procedure very easly. It is a grid of 20x20 cells. This grid enclose 3 circle. The inner circle (2 cell diameter) enclose the origin point in OpenJUMP (0,0 coordinates).The other two circle define the 10x10 cells space (the middle circle) and 20x20 cells space (the outer circle).

  1. Open the files GRID.WKT and SOURCE.DXF
  2. Make SOURCE.DXF editable and eventually group al the features (Layer View Menu>Group features)
  3. Move the feature untill its central point is on the origen (To move select it and click on Editing Toolbox>Move feature)
  4. Resize the feature untill it fits either the 20X20 cell or the 10x10 cell (this affect the display of the symbol in the cadplann plugin window preview). 20X20 size is probabily OK.

Save the file to SOURCE.WKT and go to Step 3

Step 3

The symbol is almost ready. we only need to define its dimension and line width according to Cadplans definition. If you open the SOURCE.WKT file using a TEXT editor, you probabily see a single text line which starts with one of the following word: GEOMETRYCOLLECTION..... POLYGON... LINESTRING.... POINT... Add at the beginning of the line thei text 2:20: 2 defines the line width, this value can be canged to 1 (less width) to more than 2. *2* or *1* seems the best values for symbology 20 represent the dimension, it is a sc ale factor which affect the dimension of dispalyed symbol in the Layer View. Anyhow also Cadplann plugin allows to define the dimension, 20 is probabily a good choice.

After modification you will see a line which starts with: 2:20:GEOMETRYCOLLECTION... or 2:20:POLYGON.....

Save the file to a new name e.g. SYMBOL1.WKT and go to step 4

Step 4

You need to setup the VERTEXSYMBOL plugin in OpenJUMP. Symply copy the file VERTEXSYMBOL.JAR and the folder VERTEXIMAGES in OPENJUMP\LIB\EXT\ folder. Put the file SYMBOL1.WKT in the VERTEXIMAGES folder. After you start OpenJUMP click on Menubar>plugins>Vertex Symbols to open the Vertex Symbols Dialog window. In the WKT shapes option you will see displayed your symbol.

Follow Cadplan VertexSYmbol plugin Help tutorial to customize the symbology in a project

Giuseppe Aruta

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