BASIC TRAINING FOR 2D DIGITIZATIONPART III

1. Global Mapper 12

Note! The guide was made using evaluation version of version 10, while the newest version is 12. We will have an upgrade training (2-3 days) after receiving the actual licences for the software

This guide is the first draft and the finalization of it will be done after the training.

1.1 User Interface

Tools explained

Adding layer

Open data files – this when workspace is not created

Shortcut Ctrl + O

Select file with windows selector e.g. ecw-image

You can select all supported raster types (this makes all raster types visible)

Select the file needed (this will be organized so the person digitzing will open a work space including image, map sheet frame …?). The planning and set-up for this will be done later

Exercise: Open the image mosaic provided (training folder – there are four different roughly rectified and ecw-compressed images)

Co-ordinate system

Even the co-ordinate system of the spatial data is important, it will not be configured at this phase of the work. Digitizers will have orthorectified aerial images with correct co-ordinates. The set-up of the co-ordinate system will be done later phases of the work (ArcGIS). Nevertheless in this training we will take a look of the Global Mapper capabilities to work with co-ordinate systems.

The example image is done in ERMapper and Global Mapper is capable to read Tiff co-ordinate systems

To see the existing co-ordinate system Select Tools – Configure

You can see from the configuration that the co-ordinate system is the same that given in ERMapper. You can also save this system and use it for other images/data Using the zoom and panning tools with mouse

These all work from mousea) Scroll forward – zoom inb) Scroll backward – zoom outc) Press the scroll down and drag to pan on the image

You can also zoom in with left click and zoom out with right click of the mouse

Automatic panning While digitizing, the panning works automatically at the edges of the images. Just digitize towards the edge and you will see an arrow. Click to pan

Adding and editing features

Start editing by using Digitizer tool (picture below)

Shortcut Alt+D

When editing tool is activated (one button only), the functions can be accessed by using mouse right click

From editing tools the digitizers use mainly tools 2 and 3 and the bottom tool Show Area and Line Vertices

Start by creating a line feature

Select “Create line feature”

Draw the line – when finish right click the mouse

The “Modify feature info” dialogue appears

Select feature type from the pull down menu

Note! Later on in Chapter 2 you will be introduced to the feature types. Basically digitization work covers only digitization of line features (rivers, roads and land cover areas). Areas will be labeled (point feature) and all points will have the feature class as an attribute

Click OK to confirm the editing

While editing use Ctrl+Z to undo the last operation e.g. vertice

Editing existing line

Left click on the feature you want to edit

Feature becomes selected / editable (on screen dash red line)

Right click to see the menu

Select – Show are and line vertices (vertices come visible)

Select vertice to be edited, deleted etc… by using left mouse click

Yoy can right click and select Delete the vertice or just use the shortcut Ctrl+Del to do the same

Undelete features

To enable undelete the user need to configure the vector properties

From configure, select vector display – select Render deleted featuresNow when deleting a line it will show up on the screen

Dash looking line above

To undelete – right click on selected feature

Select undelete feature

Delete vertex (“step back”)

Use Ctrl+Z

Measuring distance and areas

Activate the measurement tool by clicking the icon

Shortcut Alt+M

Right click the mouse to see the measurement menu

Set up the measurement tool to use metric distance units and Square meters for area

Draw a polygon (measurement tool) around the feature to be measured

When drawn – look the area (in sqm) from the bottom left corner of the screen

Feature info tool

Feature Info button

2. Digitizing procedures (Draft)

2.1 Preparations before starting the digitization

This part is only for the trainers. Symbols, line features and area related labels will be pre-installed to each computer used for the digitization

To enable the pre made symbology and features, you have to copy certain files to the Global mapper folder

The files needed are located in the folder called Training material

Copy all files under folder Setup to the Global Mapper folder (usually C:\Program Files\GlobalMapper10). If existing files – replace

The setup folder includes following files and a folder

Custom_are_types.txtCustom_datums.txtCustom_line_types.txtCustom_point_types.txt

GustomSymbos (Folder)

Start Global Mapper and check from the configure that the new pre-made symbols exist

Note! We are training for version 10. It seems that Version 12 offers better capabilities for this (see description below from Version 12 manual)

If you right click on the list of types, a menu will appear allowing you to save and restore your style settings using a style file. This provides an easy way to setup a set of styles to use, then restore them at a later date for use with a particular set of data.

2.2 Opening image

In the training folder there are four mosaics (one for each)

These image mosaics (each compilation of four images). Note! The rectification and stitching was done very roughly

2.3 Digitization of the line features (Rivers and Roads)

The digitization of rivers and roads are done by using line features with properties

1) Rivers

Rivers are, as seen before on, four (if river center line separately to five) different features: River (Line), Stream perennial (Line), stream intermittent (Line) and River (polygon). Normally river lines follow the mid part of the river. If the river is drawn as an area, the center line is drawn also. See below pictures for the procedures in digitizing the rivers

2) Roads

Similarly to the rivers, roads will be digitized according to the guidance.

2.4 Digitization of the land cover areas

The land cover features are digitizized by using same line type and adding symbol after. This symbol is same for all land cover types, but attributes are different. See example below

1) Create closing boundaries for the land cover area (here rice field). Use the line type land use line

2) After finishing, create the point/text feature – Right click mouse – select below

3) Add the point to the middle of the land cover and select land cover type

Symbol appears on to the land cover

The symbol is same for all land uses / covers – attributes are different

4) Check the attributes by using the feature info tool

Click on the symbol to see the attributes

The attributes include:- Feature code (done before)- Class name

2.5 Adding the symbols

There are more than 40 features that are marked as symbols. Below are shown, first the general guidelines for adding symbols and then adding some more complex feature symbols

2.6 Saving workspace

During and after digitization, save the workspace

3. Basic checks of the data (not finalized)

If two of more line features are selected, the Find Non-Connected Line Endpoints option will appear when right-clicking. Selecting this will display a dialog allowing you to either mark all line endpoints that do not connect to an endpoint (not an interior vertex) of another selected line or those line endpoints that don't connect and are within some distance of another selected line endpoint. This is a very useful feature for allowing easy identification and fixing of connectivity issues within loaded vector data.

4. Exporting to shapefiles