Convert to ArcGIS shape file
aaren
When I use either the Universal Translator or ArcCatalog's converter,
I end up with big problems. The table displays nicely, but the lat/
longs and radically incorrect - -17895520, 7339649 instead of -160,55.
This is a very small, simple table - 6 square regions. I have about
25 more tables to convert some of which have hundreds of regions and
some of those regions are very irregular with up to 200 nodes.
Can anyone take a look at my table and tell me what I'm doing wrong?
Thanks for your help. Aaren
Mike Jamieson
your source table is in lat/long, not just the session you are working
in. Open a new MapInfo and open only the table you are trying to
convert. Right click in the map window and select Current Mapper
Projection to view the native projection info.
If it is not lat/long you can "save copy as" in lat/long and then
convert the new tab file.
Mike
aaren
behrouz hoseini
I convert a Map by Mapinfo into ESRI shapefile and I am sure about Map projection in MapInfo(I am using Long/Lat Nad 83 for my maps at MapInfo) I select the same Geographic coordinate system at ArcGIS (arcCatalog and ArcMap) for current mao but when I open the converted shapefile in ArcMap it looks more stretched and wither than what it is in mapInfo.! could you please let me know what's the problem? Are Mapinfo and ArcGIS using the same projection systems or should I do any thing more?
Thanks
aaren
in the past on this forum have been told that it's just the way ESRI
and MapInfo each "interpret" the world. But I'm just learning both
software systems, so maybe someone else will have a better answer...
On Mar 25, 10:35 am, behrouz hoseini <behse...@gmail.com> wrote:
> Hi aaren,
> it seems you are working with Esri desktop Suite
> I convert a Map by Mapinfo into ESRI shapefile and I am sure about Map
> projection in MapInfo(I am using Long/Lat Nad 83 for my maps at MapInfo) I
> select the same Geographic coordinate system at ArcGIS (arcCatalog and
> ArcMap) for current mao but when I open the converted shapefile in ArcMap it
> looks more stretched and wither than what it is in mapInfo.! could you
> please let me know what's the problem? Are Mapinfo and ArcGIS using the same
> projection systems or should I do any thing more?
> Thanks
>
Tim Rideout
If something is in Lat / Long co-ordinates then it is a spherical co-ordinate system and by definition it is not projected.
As such it can not be drawn on a two dimensional computer screen.
Therefore regardless of what you might think the data is, your GIS system will have to convert it into some sort of projection in order to be able to display it. If you effectively stick up a bit of graph paper and say that each square represents one degree and plot the data accordingly, then this is in fact the Equidistant Cylindrical projection, also called plate carrée. It is not equal area, or conformal, so both shape and size are heavily distorted towards the poles (but not as much as Mercator). For anyone interested it is also one of the oldest projections, apparently going back to Marinus of Tyre in 100 AD.
MapInfo definitely uses this projection for displaying lat / long data, as indeed do a great many computer systems due to its simplicity (and the fact that each cell is a square makes it ideal for displaying anything that is pixel based).
As the other responder suggested it is perfectly possible that ArcGIS is using a different default projection like Mercator. If it does use Mercator then the map will be much more stretched North-South near the poles and it will be impossible to actually show the poles themselves as 90N goes to infinity in Mercator. Thus what looked like a circle in MapInfo would still be a circle near the equator, but would become an ellipse as you get closer to the poles in ArcGIS.
Regards
Tim
Dr Tim Rideout
Director
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From:
mapi...@googlegroups.com [mailto:mapi...@googlegroups.com] On Behalf Of behrouz hoseini
Sent: 25 March 2009 18:45
To: mapi...@googlegroups.com
Subject: [MI-L] Re: Convert to
ArcGIS shape file
Hi aaren,
it seems you are working
with Esri desktop Suite
I convert a Map by Mapinfo into ESRI shapefile and I am sure about Map
projection in MapInfo(I am using Long/Lat Nad 83 for my maps at MapInfo) I
select the same Geographic coordinate system at ArcGIS (arcCatalog and ArcMap)
for current mao but when I open the converted shapefile in ArcMap it
looks more stretched and wither than what it is in mapInfo.! could
you please let me know what's the problem? Are Mapinfo and ArcGIS using
the same projection systems or should I do any thing more?
Thanks
> Thanks for your help. Aaren<br
Warren Vick
A lot of chat on this but I don't think anyone's mentioned that your
coordinates are from a Mercator projection. The large coordinate numbers
for the part of Alaska your looking at are the give-away. If you don't
know your datum, assume WGS-84 as a starting point. Simply select this
projection for your Shapefile when using the Universal Translator.
Regards,
Warren Vick
Europa Technologies Ltd.
http://www.europa.uk.com
-----Original Message-----
From: mapi...@googlegroups.com [mailto:mapi...@googlegroups.com] On
Behalf Of aaren
Sent: 24 March 2009 02:00
To: MapInfo-L
Subject: [MI-L] Convert to ArcGIS shape file
behrouz hoseini
Seb
David R Sherrod
Hoseini,
I'm with Seb. I think the point is that you want to specify the projection for MapInfo projects, especially if you know you'll be exporting to a non-MapInfo user.
And with Tim R's advice in hand, don't use the lat-long spherical options where only a datum is specified. Because . . . (and that's the point of Rideout's answer), you'll get a default projection applied for your purposes but a non-MapInfo user may then apply a different default projection.
So save your data to a projection that is in common use for the region in which you work. If in the western (continental) U.S., for example, you might pick a transverse Mercator scheme using the appropriate UTM zone. If a map is more extensive, you'd probably use a polyconic or Albers or something else.
How to know? Look at the metadata for stuff distributed free by major agencies. Back to the western U.S., I'd look at regional GIS clearing house or Forest Service or Bureau of Land Management Web site to see how they're offering their stuff. If the data is coming from a U.S. topographic map sheet, then the projection to use might be the one the map is set in.
The goal is to lock down the details, leaving little to chance. It's the chance of default projections that is causing your headache.
--------------------------------------------
David R. Sherrod, Cascades Volcano Observatory
U.S. Geological Survey,
1300 SE Cardinal Court, Bldg. 10
Vancouver, WA 98683
voice 360-993-8915
fax 360-993-8980
dshe...@usgs.gov
-----------------------------------------
| From: | Seb <sebh...@gmail.com> |
| To: | mapi...@googlegroups.com |
| Date: | 03/26/2009 01:27 PM |
| Subject: | [MI-L] Re: Convert to ArcGIS shape file |
| Sent by: | mapi...@googlegroups.com |