TUTORIAL 1 : MAP WINDOW THE FREE SOFTWARE FOR GIS
Author: Gary Watry, Daniel P. Ames, Ph.D., Christopher Michaelis
What is MapWindow?
MapWindow is a “Programmable Geographic Information System” that supports manipulation, analysis, and viewing of geospatial data and associated attribute data in several standard GIS data formats. MapWindow was developed to address the need for a GIS programming tool that could be used in engineering research and project software, without requiring end users to purchase a complete GIS system, or become GIS experts.
For example, a researcher or company may want to deploy a tool that lets users build and interact with maps of GPS data overlaid on USGS quad maps. One approach is to build the tool as an extension to a popular GIS software, and then require users to purchase that software to run the extension. Alternatively, the company could use MapWindow as a platform and build a specialized application that does the needed function and then give it or sell it directly to end user with no need for third party software purchases.
1. ADDING VECTOR DATA
MapWindow supports three different types of Shapefiles :
- Line Shapefile: Composed of line segments that may be interconnected but don’t have to be. Can have vertices; these can be anchor points about which a line turns, for example.
- Point Shapefile: Composed of individual points. Cannot have vertices, as the point itself is the shape.
- Polygon Shapefile: Composed of solid shapes which are, in turn, composed of interconnected vertices. These are anchor points about which the lines composing the shape turn.
Add data by clicking on or by clicking on [VIEW] then [ADD LAYER]
When the Add Map Layer window opens, navigate to the data directory the user wants, then click on the GIS data the user wants to add it as a new layer in the user’s project.
Click the [OPEN] button. The new layer will be added to the user’s project
2. USING THE LEGEND TO CONTROL THE LAYERS
The legend is a graphical representation of all the map layers in the current project. The position of the legend is the left hand side of the screen. The legend offers layer manipulation functionality including but not limited to changing a layers symbology or the order of display for the layers. The legend is always displayed
- Visibility Checkbox: This indicates whether a layer is always visible (checked), always hidden (blank).
- Text: This is the name of the layer.
- Each line represents a layer of data that’s in the main view. The image to theright of the legend is an indicator to help identify the data layer. If, for example, the user had a polygon Shapefile that was filled, the color in this image would be the same as the fill color. For a line Shapefile, the color here will match the color the line is drawn with. Some layers have a plus or minus next to them. This indicates that they are collapsible or expandable. For example, a grid may have a coloring scheme indicating terrain height which may be displayed by expanding the layer, and hidden by collapsing it.
Double-click on the layer in the legend and the ‘Legend Editor’ appears
Change the text in the “Display Name” box. This will be the new layer name
The legend indicates the order that layers are drawn in. The first layer in the legend is the top layer of the map. The last layer in the legend is the bottom layer on the map. The layers are drawn from bottom up, hence the bottom layer is drawn first then the last but one layer and so on. As a result is it important to carefully order the user’s map layers so data is not obscured by layers placed on top.
Steps for Using the Changing the Drawing Order is Click and drag a layer to the desired location
3. REMOVING A LAYER FROM THE MAP
Removing a layer does not remove or delete the underlying data, it just removes the reference to the layer from the project.
Right-click on the layer in the legend, a new menu will popup –> Click on [REMOVE LAYER]
Or select the layer, click on [VIEW] then [REMOVE LAYER].
If the user right-click on a layer in the legend, a new menu will popup. By selecting [CLEAR LAYERS], it will ask the user to confirm and then remove all layers.
4. MAKING THE LAYER SCALABLE
Zoom into the scale that the user want the desired layer to appear –> Double click on the layer in the legend –> Click the ‘Dynamic Visibility’ Disabled line and a drop-down arrow will appear.
Click on the drop-down arrow –> Put a check in ‘(Use Dynamic Visibility)’
Click on the drop-down arrow again –> Click the [USE CURRENT EXTENT] button
Close the Legend Editor.
5. MAP LAYER SYMBOLIZATION
Default Symbology – When adding a new map layer to the user’s project a default symbol will be automatically generated. MapWindow will select a random color scheme and pick a pen and fill style appropriate to the geometry type of the data to be used for display purposes.
Steps for Changing the Default Symbology –> Double-click on the layer in the legend, the Legend Editor will appear
Changes made under the Display properties section will become the new default symbology
In this property edit page, the user can further modify change the color scheme (or fill color) of the layer. –> Double click on the layer to open the Legend Editor
Click on the Coloring scheme and an icon will appear –> Click on the icon and a color schema editor dialog box will show up
The user can choose a field in the shape’s attribute table to calculate the color on, and assign the number format of it
By clicking on the color, the user can change the color of each category, but the easiest to do it is to use the pre-defined color schema
The Legend Editor will also allow the user to :
• Change Display properties like Point/Line color, width, and style.
• Change layer dynamic visibility
• Change Legend properties (Expand, picture)
• Change Map Bitmap and Transparent Color.
6. ADDING A LABEL TO A LAYER
Labels are an easy way to add dynamic textual labels to geometry features on the map. MapWindow will extract a user-defined field from the map data to be used as the label text. Labels may be added to raster datasets programmatically, but not directly from within MapWindow.
Steps for Adding a Label to a Layer –> Double Click on the layer in the legend window.
Click on Label Setup –> Click on the “…” button on the Label Setup line.
Select the ‘(Label Field for First Line)’ drop-down and select the field to label with
Click [Apply] then [OK], or just [OK]
TO BE CONTINUED TO :
a. Querying Data/ Manipulating Data
b. Editing and creating
c. Spatial Analyst
GIS Tutorial | admin | July 17, 2010
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