In this module we will digitize the Darati pass trail and surrounding settlements on the 4 geo-referenced maps (Survey, Olizane, Soviet and AMS maps) and compare the accuracy of digitized features on each map by cross-referencing with actual features on the satellite map.
The Darati pass is used by shepherds for their annual migration journey across t the Pir Panjal range between the Chamba and Chenab river (Pangi) valleys. Survey map in Image 1 below shows the Darati trail (red dots) from the last settlement of Daton towards the Pir Panjral ridgeline.
Features
To digitize features on our geo-reference maps let’s create two shapefile layers. One “LineString” layer (named Hiking Trails) to hold digitized trails and one “Point” layer (called POIs) to hold digitized settlements. Choose menu “Layers”, “Create New Layer”, “Shapefile Layer” as per Images 1+2 below. Add a 30-size “Text Data” field to each layer to hold the name of digitized features.
Digitizing Features
Select the “Hiking Trails” layer, click “Toggle Editing” (Pen) Icon on the toolbar. Next click the “Add Line Feature” icon on the toolbar to start digitizing the red dotted Darati pass trail on the Survey map (similar to module 6D). Name the digitized trail as “Survey Darati pass trail”.
After completing the trail, let’s digitize the settlements surrounding the trail. Select the “POIs” layer, click “Toggle Editing” icon on the toolbar. Next click the “Add Point Feature” icon on the toolbar to start digitizing settlements. Click on each settlement near the trail and name it as per the map with “Survey” prefix. See Image 1 below.
Now, repeat the same for each other map: Olizane, Soviet and AMS. Digitize the trail and settlements on each map. Name the digitized features with corresponding prefix (“Olizane”, “Soviet”, “AMS”) to distinguish features from different maps. See Image 2+3+4 below.
Trails & Settlements
To easily distinguish the 4 digitized trails from 4 different maps let’s give them a unique color. Right click on the “Hiking Trails” layer, click “Properties”, select “Symbology”. Choose “Categorized” with Value “Name” and click “Classify” to list all unique name values. Chose red for Survey, pink for Olizane, green for Soviet and orange for AMS trail. See Image 1+2+3 below.
Assignment
Time for hands-on now to acknowledge your understanding of the concepts taught this module. Digitize the Darati pass trail and surrounding settlements for Survey, Olizane, Soviet and AMS maps in QGIS and submit in the form below.
