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| Subject: | RE: [gislist] GPS for capturing street centerline data |
| Date: |
11/13/2003 11:00:01 PM |
| From: |
Shanmugam Ganeshkumar |
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Hello SRG,
There are few issues is your survey.
With you accuracy requirement of +/- 3 meters, its much easier to
complete that task with a GOOD GPS receiver. Without any differential
correction, the accuracy in the equatorial region is the accuracy that
you are looking for. Again, you should get a good GPS receiver.
Recommended SiRF (www.sirf.com), this has few algorithms inbuilt for you
to compensate foliage blocking and urban blocking. =20
Next putting this on a 50,000 scale will raise NO accuracy issue. Since
1 mm of your map represents 50m to real and the GPS accuracy is much
less than that, you can very well use the data to fit the map without
any major issue.=20
There will be no issue in getting the road curves etc, because the
standard GPS logging rate is 1 Hz or 1 sec (unless you want a high
refresh GPS, like 100Hz, update. You got to pay heavily for that) with a
average vehicle speed of 60 kmph, you will have a position output at
every 1.6m (average).. this is more than enough for you to get the road
curve, etc.
Further more if you really like to get a centerline survey conducted,
you can look at the systems like ROMDAS. (www.romdas.com)
Good luck, hope this helps.
Cheers,
Ganesh.
-----Original Message-----
From: SRG [mailto:raghavendran@pixelinfotek.com]=20
Sent: Friday, November 14, 2003 11:30 AM
To: gislist@lists.thinkburst.com
Subject: [gislist] GPS for capturing street centerline data
Importance: High
I have been analysing the pros and cons of going for a GPS survey to
capture
the highway centerline data.(+/- 3m accuracy)
The project is basically to create a base map of the state highways from
the
available departments maps (usually 1:50000 scale).
The next item would be to perfect the centerline data captured on the
digital maps with the information collected from the GPS survey (by
driving
along the state highways with a GPS fitted vehicle).
My question is simple:
The GPS data captured will be so accurate, reflecting every small curve
on
the highway again depending on the interval at which the GPS data is
captured.
How rational it would be to use/ integrate this data on a map of 1:50000
scale?
Thanks
SRG
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