How to extract data from existing GIS map

Suppose you have to extract the map of Pokhara Region form the above given map. The image provided is in jpeg format and has no geo-reference points. We proceed from the 'admin_nepal' map provided during the GIS training and add the ICT scores to 'Attribute Tables' of the 'admin_nepal' map. For the purpose of this tutorial the following assumptions are made:



1) that you know how to install and configure Arc GIS

2) that you know how to create and add layers and you have the admin_nepal.shp file.

3) that you know how to produce the final attractive map by applying the labels, symbology, scale, etc.

Steps:

1. First we need to add the ICT scores to the admin_nepal map which looks like the following in Arc GIS:


2. Export the layer file to create a new layer named 'ICT_Nepal'. Add the layer and remove 'admin_nepal'.

3. Right Click on 'ICT_Nepal' under the Layers in the Table of Contents, and click on the 'Open Attribute Table'  as shown in the following figure: (note that the picture shows 'admin_nepal' but you advised to  work on 'ICT_Nepal')



4. The Attribute Table pops as shown below:



5. Click on the 'Options' button and then click on the 'Add Field' under the 'Options' popup as shown in the figure:



6. In the dialog box that pops up, name the field as 'ICT_Score' and set the 'field value' as float and click ok.



7. Click on the editor and click on 'Start Editing', then click on the individual score boxes under the ICT_Score field and enter the ICT scores of the corresponding districts. Don't forget to save the edits when done, before pressing on the stop edit.

  

8. Also create the Region field, for the different clusters. (You can apply the finishing touches to make the map look like the original jpeg.)



9. Now under the Selection menu click on the 'Select by Attributes' (note that I have edited the attributes on the new layer named ICT_Nepal. It is assumed you had done the same.)



10. Double click on "Region" in the popup:



11. Click on get unique values and complete the query as shown and click ok.


12. Your Selection is highlighted as shown:



13. Right click on the Layer and export the selected data. (you should know how to do this, but the picture gives a hint)


14. Congrats!! You have successfully extracted the required data.



15. Apply the finishing touches.



Note:

Your Scores are set at the default precision of 6 decimal digits. To show only one digit after the decimal perform the following operations:

a. Right click on the field 'ICT_Scores' in the attributes table and click on 'Properties':


b. The field property window pops up. Click on the box on the right of the 'Numetric' label:


c. Under the Rounding set Number of decimal places to 1.  




If you don't want to go to all this trouble then you can just erase what you don’t need in paint and prepare the final map you need from the jpeg. :D

Tutorial prepared by Saurab Dhoubhadel, ICTV, Lamjung
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About Author (Ekendra Lamsal)

This portal "ICT for Local Bodies" is written by various individuals - ICT Experts and ICT Volunteers working under MoFALD/LGCDP with an aim of integrating ICT at Local Governance. The author is this post is mentioned at the end of the article itself (with their Google+ profile alongside). Learn more about ICT4LB KMDB here.