Working with maps / image crossing 2 UTM zones
261 views
Skip to first unread message
gasenngo
Jun 5, 2010, 8:54:33 PM6/5/10
to MapInfo-L
Hi list,
I'm currently working with a satellite image, and map that crossing 2
UTM zones (zone 48 and 49).
My workflow is: i) collecting ground truth in the field using GPS and,
ii) overlay ground truth point on top of satellite image on MapInfo
for visual inspection (and later for classification in ENVI)
In the field the GPS identify the zone itself and therefore return the
coordinate in the right zone, so when I travel and collect sample
point within 1 image I'm getting points in 2 UTM zone.
My solution in the field is that, I bring a laptop in which I have 2
set of map and image each reprojected to UTM 48 and 49. I switch
between these 2 sets whenever the GPS tell me to do so, and enter the
coordinate of the point into MapInfo. The GPS point entered to MapInfo
in this way are "moved" to the right position. However in the image
classification stage, I can work with only 1 projection.
My question: Should I reproject all point in zone 48 to 49 (or vice
versa) and what is the level of spatial error for doing this.
What experiences and best practice do you have working with maps
acrrosing map zones?
Best regards,
Viet Anh
I'm currently working with a satellite image, and map that crossing 2
UTM zones (zone 48 and 49).
My workflow is: i) collecting ground truth in the field using GPS and,
ii) overlay ground truth point on top of satellite image on MapInfo
for visual inspection (and later for classification in ENVI)
In the field the GPS identify the zone itself and therefore return the
coordinate in the right zone, so when I travel and collect sample
point within 1 image I'm getting points in 2 UTM zone.
My solution in the field is that, I bring a laptop in which I have 2
set of map and image each reprojected to UTM 48 and 49. I switch
between these 2 sets whenever the GPS tell me to do so, and enter the
coordinate of the point into MapInfo. The GPS point entered to MapInfo
in this way are "moved" to the right position. However in the image
classification stage, I can work with only 1 projection.
My question: Should I reproject all point in zone 48 to 49 (or vice
versa) and what is the level of spatial error for doing this.
What experiences and best practice do you have working with maps
acrrosing map zones?
Best regards,
Viet Anh
David R Sherrod
Jun 5, 2010, 9:23:18 PM6/5/10
to mapi...@googlegroups.com
I'll be interested to see the answers that pour in, because I had a similar problem while working across UTM zones 36 and 37 in Tanzania, East Africa.
What I chose to do was convert all my data points into lat-long. You can use MapInfo to make the conversion, and then repopulate new columns in your table (for lat, long). In my case, I chose WGS84 as my datum.
that solution works handily if your imagery is in a single projection. But I also found it worked well even for my raster-image topo maps, which were in two different UTM zones. Aging MapInfo v. 8.5 handles these variations robustly.
The other reason for getting the data points in a single datum is for purposes of publication. Extra info has to be reported if traversing two UTM zones, either by way of an extra column to show the zone number, or by creating two different tables (one for each zone). It's far easier for the downstream user when given a single table with data presented as simply as possible.
Dave Sherrod
What I chose to do was convert all my data points into lat-long. You can use MapInfo to make the conversion, and then repopulate new columns in your table (for lat, long). In my case, I chose WGS84 as my datum.
that solution works handily if your imagery is in a single projection. But I also found it worked well even for my raster-image topo maps, which were in two different UTM zones. Aging MapInfo v. 8.5 handles these variations robustly.
The other reason for getting the data points in a single datum is for purposes of publication. Extra info has to be reported if traversing two UTM zones, either by way of an extra column to show the zone number, or by creating two different tables (one for each zone). It's far easier for the downstream user when given a single table with data presented as simply as possible.
Dave Sherrod
-----------------------------------------
-----mapi...@googlegroups.com wrote: -----
To: MapInfo-L <mapi...@googlegroups.com>
From: gasenngo <hoangv...@gmail.com>
Sent by: mapi...@googlegroups.com
Date: 06/05/2010 05:54PM
Subject: [MI-L] Working with maps / image crossing 2 UTM zones
--
You received this message because you are subscribed to the
Google Groups "MapInfo-L" group.To post a message to this group, send
email to mapi...@googlegroups.com
To unsubscribe from this group, send email to mapinfo-l+...@googlegroups.com
For more options, information and links to MapInfo resources (searching archives,
posting feature requests, to visit our Wiki, visit the Welcome page at http://groups.google.com/group/mapinfo-l?hl=en
Reply all
Reply to author
Forward
0 new messages