Re: [datameet] Guidance on digitizing boundaries

[Nikhil VJ]

Hi Gufran,

I had done georeferencing in QGIS of Pune's latest (2017) ward maps when
they were published:
https://github.com/datameet-pune/datameet-pune.github.io/tree/master/maps

It's been used by lot of folks since then as I guess official digital
shapefiles were never published though internally the corporation does seem
to be using their own. There is an obvious disclaimer that it was manually
done by volunteer and I've included the original maps and links for
referencing - use at own risk, no guarantees. Corrections in case anything
is wrong are most welcome.

I've found three ways to do the first crucial step of *geo-referencing* the
pdf / image map:

There is one traditional way there which involves more work, but has lot
more options like if your pdf/image is relatively distorted in proportions
compared to actual map then you can do things to rectify. Sharing its link:
https://www.qgistutorials.com/en/docs/3/georeferencing_basics.html
This involves clicking and marking common points between your image/pdf map
and the actual map.

There is another quicker plugin in QGIS I had found later, which uses a
different and much quicker approach, but works well only if your pdf/jpg is
already good in proportions and doesn't have too much distortion.
https://gvellut.github.io/FreehandRasterGeoreferencer/
This involves "floating" the pdf/image over the map and resizing, rotating
it till it fits properly.

Then, there is a website called mapwarper that uses the the same approach
as first solution but more streamlined (albeit with fewer power options):
http://mapwarper.net/
Once the "warping" onto map is done, you can download the georeferenced TIF
and load it on QGIS. Or you can publish your map, copy the tile layer
string from the export section and import in QGIS as a XYZ tiles map layer.

Once the georeferencing is complete, you have a image layer properly fixed
to lat-long map, which moves and zooms with the map. Now you can create an
empty polygons shapefile and start manually tracing the boundaries.

Tips from digitizing experience:
1. It's good to use Snap settings to make your boundaries snap to each
other properly so you don't leave out slivers of no-mans-land or overlaps
between wards. I found 20 pixels snap to be good.
2. These ward boundaries oftentimes follow along canals and roads. So, you
can add a map satellite view background layer and keep it semi-transparent
to assist you.
3. Bring in any other boundaries file (like district etc) which might help
you start from the outside.
4. If using the common points method, try to have a good spread of points.
Avoid keeping any 3 consecutive points in a line, as small errors can get
magnified. Crossroads/chowks are good places to pin.

Some links and video online that can guide through this process:
https://www.qgistutorials.com/en/docs/digitizing_basics.html
https://www.cadlinecommunity.co.uk/hc/en-us/articles/36291898-QGIS-How-do-you-Snap-and-Trace-when-Digitising-
https://www.youtube.com/results?search_query=digitizing+map+boundaries

All the best, and do share when done - it'll be good to see more ward
boundaries come up from MH!

--
Cheers,
Nikhil VJ
https://nikhilvj.co.in


On Mon, Dec 28, 2020 at 10:30 AM Digvijay Bendrikar Shinde <
digvijaybendrikarshi...@gmail.com> wrote:

> Thanks Ar Akshit,
>
> MRSAC don't have corporation ward wise boundaries PDF, they have revenue
> village and outer boundaries of towns and cities... But within the cities
> details are Missing.
>
> Thanks about Karnataka link, will check.
>
> Regards
> Digvijay
> (PhD scholar at CTARA, IIT Bombay)
>
> On Sun, Dec 27, 2020, 4:26 PM Akshit Shah  wrote:
>
>> Hi Gufran and Digvijay,
>>
>> You can get the pdf copy of maps from the following portal:
>> https://mrsac.gov.in/MRSAC/map/map
>>
>> you can either import pdf in AutoCAD and separate the admin boundary
>> layers > georeference them > and convert them to shapefile. your
>> digitisation effort will be saved if the pdf has vector elements in it.
>>
>> for Karnataka State there is a portal where you can find Admin boundary
>> upto Town, wards and village level:
>> https://kgis.ksrsac.in/kgis/downloads.aspx#
>>
>> On Sun, Dec 27, 2020 at 7:08 AM Gufran Pathan 
>> wrote:
>>
>>> Hi team,
>>>
>>> I am trying to digitize ward boundaries for the city of Akola
>>> (Maharashtra) - create shape files so that I can visualize them along with
>>> associated data. I'm reaching out to get some guidance on how one would go
>>> about doing this? What does the process look like at a high-level? Does one
>>> get physical / PDF copies of the map with boundaries and then 'digitize'
>>> it? What tools are typically used in the digitization process? Is it
>>> largely a manual activity (does one need to manually draw the boundaries on
>>> a tool using the reference)?
>>>
>>> I'd love any guidance and further readings that would help me with this.
>>>
>>> Thanks,
>>> Gufran
>>>
>>> --
>>> Datameet is a community of Data Science enthusiasts in Ind

Re: [datameet] Guidance on digitizing boundaries

[Digvijay Bendrikar Shinde]

Thanks Ar Akshit,

MRSAC don't have corporation ward wise boundaries PDF, they have revenue
village and outer boundaries of towns and cities... But within the cities
details are Missing.

Thanks about Karnataka link, will check.

Regards
Digvijay
(PhD scholar at CTARA, IIT Bombay)

On Sun, Dec 27, 2020, 4:26 PM Akshit Shah  wrote:

> Hi Gufran and Digvijay,
>
> You can get the pdf copy of maps from the following portal:
> https://mrsac.gov.in/MRSAC/map/map
>
> you can either import pdf in AutoCAD and separate the admin boundary
> layers > georeference them > and convert them to shapefile. your
> digitisation effort will be saved if the pdf has vector elements in it.
>
> for Karnataka State there is a portal where you can find Admin boundary
> upto Town, wards and village level:
> https://kgis.ksrsac.in/kgis/downloads.aspx#
>
> On Sun, Dec 27, 2020 at 7:08 AM Gufran Pathan 
> wrote:
>
>> Hi team,
>>
>> I am trying to digitize ward boundaries for the city of Akola
>> (Maharashtra) - create shape files so that I can visualize them along with
>> associated data. I'm reaching out to get some guidance on how one would go
>> about doing this? What does the process look like at a high-level? Does one
>> get physical / PDF copies of the map with boundaries and then 'digitize'
>> it? What tools are typically used in the digitization process? Is it
>> largely a manual activity (does one need to manually draw the boundaries on
>> a tool using the reference)?
>>
>> I'd love any guidance and further readings that would help me with this.
>>
>> Thanks,
>> Gufran
>>
>> --
>> Datameet is a community of Data Science enthusiasts in India. Know more
>> about us by visiting http://datameet.org
>> ---
>> You received this message because you are subscribed to the Google Groups
>> "datameet" group.
>> To unsubscribe from this group and stop receiving emails from it, send an
>> email to datameet+unsubscr...@googlegroups.com.
>> To view this discussion on the web visit
>> https://groups.google.com/d/msgid/datameet/5231d38d-12a5-4563-b2c2-0c4a449923f0n%40googlegroups.com
>> 
>> .
>>
>
>
> --
> Warm Regards,
>
> *Ar. Akshit Shah*
> Associate - Research Service, Cushman & Wakefield India
> M.Tech (Infra), IIT KGP | B.Arch, VNIT Nagpur
> +91 80077 62247
> Linkedin * | *Cushman &
> Wakefield India
> 
>
> --
> Datameet is a community of Data Science enthusiasts in India. Know more
> about us by visiting http://datameet.org
> ---
> You received this message because you are subscribed to the Google Groups
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> To view this discussion on the web visit
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> 
> .
>

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us by visiting http://datameet.org
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Re: [datameet] Guidance on digitizing boundaries

[Akshit Shah]

Hi Gufran and Digvijay,

You can get the pdf copy of maps from the following portal:
https://mrsac.gov.in/MRSAC/map/map

you can either import pdf in AutoCAD and separate the admin boundary layers
> georeference them > and convert them to shapefile. your digitisation
effort will be saved if the pdf has vector elements in it.

for Karnataka State there is a portal where you can find Admin boundary
upto Town, wards and village level:
https://kgis.ksrsac.in/kgis/downloads.aspx#

On Sun, Dec 27, 2020 at 7:08 AM Gufran Pathan 
wrote:

> Hi team,
>
> I am trying to digitize ward boundaries for the city of Akola
> (Maharashtra) - create shape files so that I can visualize them along with
> associated data. I'm reaching out to get some guidance on how one would go
> about doing this? What does the process look like at a high-level? Does one
> get physical / PDF copies of the map with boundaries and then 'digitize'
> it? What tools are typically used in the digitization process? Is it
> largely a manual activity (does one need to manually draw the boundaries on
> a tool using the reference)?
>
> I'd love any guidance and further readings that would help me with this.
>
> Thanks,
> Gufran
>
> --
> Datameet is a community of Data Science enthusiasts in India. Know more
> about us by visiting http://datameet.org
> ---
> You received this message because you are subscribed to the Google Groups
> "datameet" group.
> To unsubscribe from this group and stop receiving emails from it, send an
> email to datameet+unsubscr...@googlegroups.com.
> To view this discussion on the web visit
> https://groups.google.com/d/msgid/datameet/5231d38d-12a5-4563-b2c2-0c4a449923f0n%40googlegroups.com
> 
> .
>


-- 
Warm Regards,

*Ar. Akshit Shah*
Associate - Research Service, Cushman & Wakefield India
M.Tech (Infra), IIT KGP | B.Arch, VNIT Nagpur
+91 80077 62247
Linkedin * | *Cushman &
Wakefield India


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