Hey,
Since many people on this list have attended workshops or even done some mapping/tracing work, I thought I would ask some questions here -
1) Suppose you are walking on a particular street - 2 way street even - you encounter a few shops - say a big Sweet and Snacks / Hotel / School / anything, on the same street. Now how do you put those on the maps while GPS tracking and then tracing the map on the computer?
I mean, the to reach the shop, you have to walk good 5 meters or such - at times - depending on width of foot path or such. Now those paths are not roads really, and they can vary from place to place. How to tackle such offsets ?
2) Suppose you have tracked certain part of your town or your route from your home to airport near your city. Then you fly to another city and then restart the GPS device. At that point the device generally has to re-initiate itself to capture/detect the satellites ( which it has to do anyway incase you turn off and then switch on a gps device - atleast in some devices that I have seen ). Anyway after it has done that, it calculates the Longitude and Latitude and hence the current position. What happens in this case is, the GPS device draws a straight line from City A to City B. Is there a way to avoid that / tackle that ?
Any pointers ? Thanks in advance.
Cheers!
Pradeepto
hi !
On Wed, Jun 25, 2008 at 1:39 PM, Pradeepto Bhattacharya pradeeptob@gmail.com wrote:
Hey,
Since many people on this list have attended workshops oreven done some mapping/tracing work, I thought I would ask some questions here -
1) Suppose you are walking on a particular street - 2 waystreet even - you encounter a few shops - say a big Sweet and Snacks / Hotel / School / anything, on the same street. Now how do you put those on the maps while GPS tracking and then tracing the map on the computer?
Mark what you want as waypoints .so its always a good decision to carry a notepad and a pen while mapping.
I mean, the to reach the shop, you have to walk good 5meters or such - at times - depending on width of foot path or such. Now those paths are not roads really, and they can vary from place to place. How to tackle such offsets ?
Offsets can only be tackle when you are actually editing the track for maps . JOSM , potlaych , mapnik all provide presets for this .again pen and paper comes to help .
2) Suppose you have tracked certain part of your town oryour route from your home to airport near your city. Then you fly to another city and then restart the GPS device. At that point the device generally has to re-initiate itself to capture/detect the satellites ( which it has to do anyway incase you turn off and then switch on a gps device - atleast in some devices that I have seen ). Anyway after it has done that, it calculates the Longitude and Latitude and hence the current position. What happens in this case is, the GPS device draws a straight line from City A to City B. Is there a way to avoid that / tackle that ?
well just dont put that part while editing the tracks/routes . its always better to mark waypoints of imporatnt cities in between routes . atleast thats what i did from delhi to kolkata and off course take help of yahoo maps as the collaborate with OSM with thsi regard . more details can be found at osm-talk list
Any pointers ? Thanks in advance. Cheers!Pradeepto
happy mapping
Hi,
On Wed, Jun 25, 2008 at 1:50 PM, Subhodip Biswas subhodipbiswas@gmail.com wrote:
well just dont put that part while editing the tracks/routes . its
Oki doki.
always better to mark waypoints of imporatnt cities in between routes . atleast thats what i did from delhi to kolkata and off course take
I would be very scared if you were in flying in the same plane as that of me ;). It generally is advised by the crew to turn off electronic devices after the plane's doors are closed / during take off / landing and communication devices are a strict no-no throught out the flight. And even if it were allowed, it would slightly difficult to mark way points from few thousand feet ;)
The question was based on the fact that, while flying a device would have to switched off until the destination has been reached. Anyway, thanks to you and JTD, I got the idea now.
Cheers!
Pradeepto
On Wednesday 25 Jun 2008 18:40, Pradeepto Bhattacharya wrote:
I would be very scared if you were in flying in thesame plane as that of me ;). It generally is advised by the crew to turn off electronic devices after the plane's doors are closed / during take off / landing and communication devices are a strict no-no throught out the flight. And even if it were allowed, it would slightly difficult to mark way points from few thousand feet ;)
That is a load of rubbish by the AHs who man these flights and make the rules. You would not have survived a plane with navigation equipment so poorly shielded against rfi. Every vsat terminal blasts several watts of rf in a tightly focussed beam. Your pissy phone can barely emit 1 watt and that too omni directional. Most other battery powered equipment cant even disturb the reception of an am reciever. And dont forget TV and FM stations - several Kilowatts for tv 15KW being the norm, 400W for FM.
Next time you can give the airhostess a lesson in RF transmissions ;-)
On Wednesday 25 Jun 2008 13:39, Pradeepto Bhattacharya wrote:
Hey,
Since many people on this list have attended workshops oreven done some mapping/tracing work, I thought I would ask some questions here -
1) Suppose you are walking on a particular street - 2 waystreet even - you encounter a few shops - say a big Sweet and Snacks / Hotel / School / anything, on the same street. Now how do you put those on the maps while GPS tracking and then tracing the map on the computer?
I mean, the to reach the shop, you have to walk good5 meters or such - at times - depending on width of foot path or such. Now those paths are not roads really, and they can vary from place to place. How to tackle such offsets ?
GPS data is accurate to 2.5 mtr in a few, 5mtr for most under ideal conditions. Usually 10 Mtr. So you are anyway off by a few meters. For the accuracies that you are talking of you would require survey quality gps AND DGPS with correction data for your locality.
2) Suppose you have tracked certain part of your town oryour route from your home to airport near your city. Then you fly to another city and then restart the GPS device. At that point the device generally has to re-initiate itself to capture/detect the satellites ( which it has to do anyway incase you turn off and then switch on a gps device - atleast in some devices that I have seen ). Anyway after it has done that, it calculates the Longitude and Latitude and hence the current position. What happens in this case is, the GPS device draws a straight line from City A to City B. Is there a way to avoid that / tackle that ?
That is a function of the handheld (which is a small computer with all sorts of features attached to an internal gps) not a function of the gps. You will have to check your particular handheld gps user manual on how to stop and start new traces.
Any pointers ? Thanks in advance. Cheers!Pradeepto
The KDE Project : http://www.kde.org KDE India : http://in.kde.org Mailing List : http://mail.kde.org/mailman/listinfo/kde-india
Hey,
On Wed, Jun 25, 2008 at 2:49 PM, jtd jtd@mtnl.net.in wrote:
GPS data is accurate to 2.5 mtr in a few, 5mtr for most under ideal conditions. Usually 10 Mtr. So you are anyway off by a few meters. For the accuracies that you are talking of you would require survey quality gps AND DGPS with correction data for your locality.
Hmm, not sure about different GPS models, the one I have used I noticed that it could give me 2 different ( parallel ) tracks for walking on extreme sides of a 2 way road and that too in New Panvel where the roads are far less wide compared to those in New Delhi ;).
What is "DGPS with correction data for your locality." ?
Cheers!
Pradeepto
On Wednesday 25 Jun 2008 18:28, Pradeepto Bhattacharya wrote:
Hmm, not sure about different GPS models, the one I haveused I noticed that it could give me 2 different ( parallel ) tracks for walking on extreme sides of a 2 way road and that too in New Panvel where the roads are far less wide compared to those in New Delhi ;).
The two line are relative to itself. I absolute terms you still dont know if the lines are accurate. If you take another model of gps, there will (proly) be a slight difference. If you take the reading under cloudy skies there may be difference.
What is "DGPS with correction data for your locality." ?
Differential GPS. A method of correcting gps errors. Other newer methods are WAAS (Wide Area Augmentation System) and SBAS (Satellite Based Augmentation Systems).
http://www.kowoma.de/en/gps/waas_egnos.htm
GPS systems have errors due to atmospheric / ionospheric delays, reflected signals, timing inaccuracies and sattelite drift. Theses errors (except atmospheric) are nearly the same for an area of a few 100 sqKm. So if you can fix a location triangulated by standard surveying techniques and then take the difference with the one shown by the gps, you have an error correction factor available. Broadcast this factor by radio or over the net or by satellite. Recieve the error factor, feed it to the gps and correct your gps reading.
Very useful when surveying and mapping - given the astronomical prices of real estate.
On 26-Jun-08, at 11:36 AM, jtd wrote:
Very useful when surveying and mapping - given the astronomical prices of real estate.
better to use a laser range finder for this - gps wont cut it
On Friday 27 Jun 2008 11:03, Kenneth Gonsalves wrote:
On 26-Jun-08, at 11:36 AM, jtd wrote:
Very useful when surveying and mapping - given the astronomical prices of real estate.
better to use a laser range finder for this - gps wont cut it
Sort of True. Survey quality gps will give you repeatability - the offset will be consistent and the distance between two points over a few Km will be accurate. But the position wrt to a standard survey may be way off. Thus results (conventional survey or gps) are open to interpretation.
On 27-Jun-08, at 1:15 PM, jtd wrote:
better to use a laser range finder for this - gps wont cut it
Sort of True. Survey quality gps will give you repeatability - the offset will be consistent and the distance between two points over a few Km will be accurate. But the position wrt to a standard survey may be way off. Thus results (conventional survey or gps) are open to interpretation.
I tried to do a couple of golf courses with gps - total failure. With the laser range finder (and not a very expensive one, I was able to get accuracy within a yard - which is acceptable for a golf course.
On Saturday 28 Jun 2008 10:42, Kenneth Gonsalves wrote:
On 27-Jun-08, at 1:15 PM, jtd wrote:
better to use a laser range finder for this - gps wont cut it
Sort of True. Survey quality gps will give you repeatability - the offset will be consistent and the distance between two points over a few Km will be accurate. But the position wrt to a standard survey may be way off. Thus results (conventional survey or gps) are open to interpretation.
I tried to do a couple of golf courses with gps - total failure. With the laser range finder (and not a very expensive one, I was able to get accuracy within a yard - which is acceptable for a golf course.
You should get upto 2.5 m with a 32 ch device. Of course only twelve are used. but it picks a good mix of overhead and horizon sats. try by keeping the reciever still on the ground. For higher accuracies survey quality gps. You should get accuracy of 1 mm/Km. Also by fixing two points accurately on the periphery by non gps means, you could get a deviation figure and correct your readings. You will have to take the correction every few hrs as ionospheric delays vary with sun activity. I have only a vague understanding of the issues involved so dont bet the house on data from this thread.
On 28-Jun-08, at 11:37 AM, jtd wrote:
Also by fixing two points accurately on the periphery by non gps means,
how is this done? I am told that in America there are markers everywhere giving reference points. The only one in India I have seen is at St Thomas Mount where they started the survey of India.
you could get a deviation figure and correct your readings. You will have to take the correction every few hrs as ionospheric delays vary with sun activity.
I tried marking the main fountain in Ooty - walked around it 3 times and marked the waypoints. They were all over the place. I was using a garmin device and it was showing accuracy of 30-35 metres on that day.
On Saturday 28 Jun 2008 12:11, Kenneth Gonsalves wrote:
On 28-Jun-08, at 11:37 AM, jtd wrote:
Also by fixing two points accurately on the periphery by non gps means,
http://www.iers.org/ Essentially use star data to locate a point on earth, then reference that to WGS84.
About Indian geodectic state of affairs
http://www.mycoordinates.org/geodetic-infrastructure.php
Might be good idea to contact the Survey of India, Hyderabad.
But if you do not need the absolute coordinates. Just mark two points 1Km apart accurately aligned NS. This is your baseline. Note a few coordinates with a gps placed flat on the ground. Calculate the distance between the coords. The error is your correction factor. Also available on the net is rinex data which gives you the ionospheric variation for a particular area, from which one can estimate error.
how is this done? I am told that in America there are markers everywhere giving reference points. The only one in India I have seen is at St Thomas Mount where they started the survey of India.
Yes. A steel rod fixed in concrete in the ground. also known as a geodectic reference point.
you could get a deviation figure and correct your readings. You will have to take the correction every few hrs as ionospheric delays vary with sun activity.
http://www.precision-gps.org./Mathematics.htm
I tried marking the main fountain in Ooty - walked around it 3 times and marked the waypoints. They were all over the place. I was using a garmin device and it was showing accuracy of 30-35 metres on that day.
That is because it's proly 12 channel, has an internal antenna and no waas / sbas.
Since India has launched GIS sats. I am inclined towards the fact that geodectic info must be available either at isro or Survey of India. Perhaps an approach by some institution (HBCSE, AU-KBC) may prise it out.
On 28-Jun-08, at 6:35 PM, jtd wrote:
About Indian geodectic state of affairs
omg - I didnt think it was this bad - we have a lot of work ahead of us
On Saturday 28 Jun 2008 19:30, Kenneth Gonsalves wrote:
On 28-Jun-08, at 6:35 PM, jtd wrote:
About Indian geodectic state of affairs
omg - I didnt think it was this bad - we have a lot of work ahead of us
Indeed. Infact several high security areas blocked by googlemaps after the rukus by the indian government are areas several 10s of Km off mark. Result - adjoining villages and roads are not visible and the high security area nicely exposed. Our official maps must be a real disaster.
On 25-Jun-08, at 1:39 PM, Pradeepto Bhattacharya wrote:
- Suppose you are walking on a particular street - 2 way
street even - you encounter a few shops - say a big Sweet and Snacks / Hotel / School / anything, on the same street. Now how do you put those on the maps while GPS tracking and then tracing the map on the computer?
paper and pen
I mean, the to reach the shop, you have to walk good 5meters or such - at times - depending on width of foot path or such. Now those paths are not roads really, and they can vary from place to place. How to tackle such offsets ?
measure it
2) Suppose you have tracked certain part of your town oryour route from your home to airport near your city. Then you fly to another city and then restart the GPS device. At that point the device generally has to re-initiate itself to capture/detect the satellites ( which it has to do anyway incase you turn off and then switch on a gps device - atleast in some devices that I have seen ). Anyway after it has done that, it calculates the Longitude and Latitude and hence the current position. What happens in this case is, the GPS device draws a straight line from City A to City B. Is there a way to avoid that / tackle that ?
no way to avoid it - delete the line
Hi,
On Thu, Jun 26, 2008 at 8:36 AM, Kenneth Gonsalves lawgon@au-kbc.org wrote:
On 25-Jun-08, at 1:39 PM, Pradeepto Bhattacharya wrote:
- Suppose you are walking on a particular street - 2 way
street even - you encounter a few shops - say a big Sweet and Snacks / Hotel / School / anything, on the same street. Now how do you put those on the maps while GPS tracking and then tracing the map on the computer?
paper and pen
Actually some devices can store names of the way point. That was not the problem at all. The problem is about offsets and resultant accuracy of maps.
I mean, the to reach the shop, you have to walk good 5meters or such - at times - depending on width of foot path or such. Now those paths are not roads really, and they can vary from place to place. How to tackle such offsets ?
measure it
That might be possible ( if at all ) if I am doing nothing else but mapping, but not when I am on my morning/evening walk or just going from one place to another in a vehicle/train/whatever ( and mapping on the sidelines ) and can't stop to do such measurements. Plus, what would be the use of such measurements anyway? My concern with offsets is the accuracy of the resultant map and positions of waypoints ( shops/schools etc ) on the map.
Cheers!
Pradeepto
On 26-Jun-08, at 9:26 AM, Pradeepto Bhattacharya wrote:
measure it
That might be possible ( if at all ) if I am doing nothingelse but mapping, but not when I am on my morning/evening walk or just going from one place to another in a vehicle/train/whatever ( and mapping on the sidelines ) and can't stop to do such measurements.
if you cant, dont - go do something else and leave mapping to people with more commitment
Hi,
On Thu, Jun 26, 2008 at 9:39 AM, Kenneth Gonsalves lawgon@au-kbc.org wrote:
On 26-Jun-08, at 9:26 AM, Pradeepto Bhattacharya wrote:
measure it
That might be possible ( if at all ) if I am doing nothingelse but mapping, but not when I am on my morning/evening walk or just going from one place to another in a vehicle/train/whatever ( and mapping on the sidelines ) and can't stop to do such measurements.
if you cant, dont - go do something else and leave mapping to people with more commitment
I see why there was a reason to get personal or rude at all. I was honestly asking for tips on how things are done.
Cheers!
Pradepeto
On 26-Jun-08, at 9:40 AM, Pradeepto Bhattacharya wrote:
On Thu, Jun 26, 2008 at 9:39 AM, Kenneth Gonsalves <lawgon@au- kbc.org> wrote:
On 26-Jun-08, at 9:26 AM, Pradeepto Bhattacharya wrote:
measure it
That might be possible ( if at all ) if I am doingnothing else but mapping, but not when I am on my morning/evening walk or just going from one place to another in a vehicle/train/whatever ( and mapping on the sidelines ) and can't stop to do such measurements.
if you cant, dont - go do something else and leave mapping to people with more commitment
I see why there was a reason to get personal or rude atall. I was honestly asking for tips on how things are done.
nothing rude or personal here - it is just that mapping is also hard work. 2-3 metres inaccuracy in the devices means physically getting down and working at accuracy. Indians? working? taking trouble? sheesh - *that* is rude.
On 26-Jun-08, at 9:53 AM, Kenneth Gonsalves wrote:
On 26-Jun-08, at 9:40 AM, Pradeepto Bhattacharya wrote:
On Thu, Jun 26, 2008 at 9:39 AM, Kenneth Gonsalves <lawgon@au- kbc.org> wrote:
On 26-Jun-08, at 9:26 AM, Pradeepto Bhattacharya wrote:
measure it
That might be possible ( if at all ) if I am doingnothing else but mapping, but not when I am on my morning/evening walk or just going from one place to another in a vehicle/train/whatever ( and mapping on the sidelines ) and can't stop to do such measurements.
if you cant, dont - go do something else and leave mapping to people with more commitment
I see why there was a reason to get personal or rude atall. I was honestly asking for tips on how things are done.
nothing rude or personal here - it is just that mapping is also hard work. 2-3 metres inaccuracy in the devices means physically getting down and working at accuracy. Indians? working? taking trouble? sheesh - *that* is rude.
and looking at panvel - http://www.openstreetmap.org/edit? lat=11.404&lon=76.713&zoom=11, nothing here. You could atleast trace out that river (dont worry about accuracy)
On Thursday 26 Jun 2008 09:53, Kenneth Gonsalves wrote:
nothing rude or personal here - it is just that mapping is also hard work. 2-3 metres inaccuracy in the devices means physically getting down and working at accuracy. Indians? working? taking trouble? sheesh - *that* is rude.
http://www.gisdevelopment.net/technology/gps/techgp0022.htm
IIT apparently has implemented a SBAS repo. If some one could get it published on the web.
Would reduce errors very substantially. And save some labour too.
digging in google threw this up
http://igs.bkg.bund.de/admin/db/db_edit.php?id=1004&table=Station
One station in B'lore for the whole country. Way to go.
Wonder what are we launching gis satellites for?
Pradeepto Bhattacharya wrote:
That might be possible ( if at all ) if I am doing nothing else but mapping, but not when I am on my morning/evening walk or just going from one place to another in a vehicle/train/whatever ( and mapping on the sidelines ) and can't stop to do such measurements. Plus, what would be the use of such measurements anyway? My concern with offsets is the accuracy of the resultant map and positions of waypoints ( shops/schools etc ) on the map.
Is there an easier way of mapping by using high resolution maps from googlemaps or any other provider and converting them into drawings. All the street lamp tops as well as building tops can be painted with special identification code patterns that can be observed from space and can be marked clearly in the satt. images. This reduces the trouble of people having to manually walk everywhere with a device in hand. A software that can convert the optical pattern code into text, automatically adds relevant content into the converted maps. Just my 2p.
"Laziness is the mother of innovation."
On 26-Jun-08, at 12:30 PM, Rony wrote:
Pradeepto Bhattacharya wrote:
That might be possible ( if at all ) if I am doing nothing else but mapping, but not when I am on my morning/evening walk or just going from one place to another in a vehicle/train/whatever ( and mapping on the sidelines ) and can't stop to do such measurements. Plus, what would be the use of such measurements anyway? My concern with offsets is the accuracy of the resultant map and positions of waypoints ( shops/schools etc ) on the map.
Is there an easier way of mapping by using high resolution maps from googlemaps or any other provider
copyright problems with google maps - we have to make do with yahoo images
Kenneth Gonsalves wrote:
On 26-Jun-08, at 12:30 PM, Rony wrote:
Pradeepto Bhattacharya wrote:
That might be possible ( if at all ) if I am doing nothing else but mapping, but not when I am on my morning/evening walk or just going from one place to another in a vehicle/train/whatever ( and mapping on the sidelines ) and can't stop to do such measurements. Plus, what would be the use of such measurements anyway? My concern with offsets is the accuracy of the resultant map and positions of waypoints ( shops/schools etc ) on the map.
Is there an easier way of mapping by using high resolution maps from googlemaps or any other provider
copyright problems with google maps - we have to make do with yahoo images
Thats not a problem. The main part of the solution is to optically mark lamp posts and building tops with optical patterns that represent coded text. The lamp posts provide the road path and buildings the content. Since the satt. is already in space, the only manual labour is to plant plastic or wooden sheets painted with pre-programmed codes. The satt. camera image is then processed in something like an OCR and we get absolute accurate maps with no errors.
On Thursday 26 Jun 2008 12:30, Rony wrote:
Is there an easier way of mapping by using high resolution maps from googlemaps or any other provider and converting them into drawings.
Possible except that the images are quite inaccurate. The sats photograph a swath of the earth's surface. The edges are distorted and corrected mathematically based on assumptions. Quite often these assumptions are wrong. And data from two sources will deviate in weird ways with skews and offsets.
All the street lamp tops as well as building tops can be painted with special identification code patterns that can be
the cost of paint would be more than the cost of handing out gpss to people. Not to mention pollution
observed from space and can be marked clearly in the satt. images. This reduces the trouble of people having to manually walk everywhere with a device in hand. A software that can convert the optical pattern code into text, automatically adds relevant content into the converted maps. Just my 2p.
Extremely error prone. Read 1st para.
jtd wrote:
On Thursday 26 Jun 2008 12:30, Rony wrote:
observed from space and can be marked clearly in the satt. images. This reduces the trouble of people having to manually walk everywhere with a device in hand. A software that can convert the optical pattern code into text, automatically adds relevant content into the converted maps. Just my 2p.
Extremely error prone. Read 1st para.
It would be similar to maps.google.com images in mixed mode....satt. and outline with text over it. At very close zooms over small areas, the curvature of the earth may be easy to correct. Something like an areal photo from a spy plane. .
On Friday 27 Jun 2008 23:32, Rony wrote:
jtd wrote:
On Thursday 26 Jun 2008 12:30, Rony wrote:
observed from space and can be marked clearly in the satt. images. This reduces the trouble of people having to manually walk everywhere with a device in hand. A software that can convert the optical pattern code into text, automatically adds relevant content into the converted maps. Just my 2p.
Extremely error prone. Read 1st para.
It would be similar to maps.google.com images in mixed mode....satt. and outline with text over it. At very close zooms over small areas,
Wrong. Checkout Surat.
the curvature of the earth may be easy to correct. Something like an areal photo from a spy plane. .
Its a wrong approach. You can use such a method as a rough guide only. There are numerous issues with the type of projections, proximity to the pole etc - rendering a sphere on a flat surface - apart from the problems with sat imagery. Basically the pixmaps you see are pre-rendered images from a geodatabase overlayed with satellite imagery, Out of which you are trying to create a GIS database. The process is not bidirectional. You MUST generate an accurate database for substantial areas to have useable data. BTW street maps are a minor part of a GIS system. Real use happens when you can overlay info like disease spreads, water sheds, insect vectors etc, etc. and come up with a basis to use these as predictors of problems. Then use these as guides to intervene. e.g mindless spraying of inseticide to prevent malaria in Mumbai and Navi mumbai. Is any body checking the effectiveness of such methods and how it is actually helping the mosquitoes by killing natural predators (who btw are several orders of magnitude more effective than ddt / malthion ). Being directed to the nearest dhaba by googlemaps is great but ensuring you dont get hepatitis-B on the house is proly a lot better.
The point here is that mapping is a tedious affair. Shortcuts result in poor quality database which inevitably causes bitrot. Besides the copyright issues there are technical issues too - both rather difficult to solve. Make the extra effort to prevent bitrot and legal hassles. The FOSS approach is a perfect fit for GIS.
On 28-Jun-08, at 11:25 AM, jtd wrote:
The point here is that mapping is a tedious affair. Shortcuts result in poor quality database which inevitably causes bitrot. Besides the copyright issues there are technical issues too - both rather difficult to solve. Make the extra effort to prevent bitrot and legal hassles. The FOSS approach is a perfect fit for GIS.
also do not forget that google imagery, in India anyway is anything from 1 to 3 years old, depending on the area.
jtd wrote:
The point here is that mapping is a tedious affair. Shortcuts result in poor quality database which inevitably causes bitrot. Besides the copyright issues there are technical issues too - both rather difficult to solve. Make the extra effort to prevent bitrot and legal hassles. The FOSS approach is a perfect fit for GIS.
True!
-
jtd -
Kenneth Gonsalves -
Pradeepto Bhattacharya -
Rony -
Subhodip Biswas