A map projection is any method of representing the surface of a sphere or other three-dimensional body on a plane

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Projected maps don't overlap

I am very new to arcGIS and so apologise if this is a really simple question, but it has had me (and what I can find on the internet beat for 2 days now. I am trying to build a series of layers of ...
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How can I transform GCS_North_American_1983 to GCS_WGS_1984?

I posted a thread today describing a shift in some of the NRC data (not all). Apparently, this shift has to do with conversion between Geographic coordinates, latitude and longitude and Transverse ...
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377 views

Is there a projection issue with the NRC Canada Atlas hydrology data?

I have been using the Natural Resources Canada (NRC) data for various generalized maps but it is not until now when i overlaid higher resolution features obtained from the provincial government ...
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ArcGIS 10 British National Grid Transformation

In ArcGIS 10 a new transformation has been added for converting between WGS84 and British National Grid. What is OSGB_1936_To_WGS_1984_NGA_7PAR? How should it be used when compared with the other ...
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How to change default projection in ArcPad 10?

Is there a way to set a default projection in ArcPad 10? The only way I can tell is by creating a quickProject based on a project that contains a shapefile with the same projection, but that's just ...
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Does a projection's WKT reflect the computer's locale?

This should be quick - we're trying to determine if there are problems parsing some WKT text because the system locale considers the decimal separator to be a comma instead of a period. Anyone know? ...
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Derive WGS84 Longitude & Latitude from British Northings & Eastings

I'm looking for a fairly simple way to append columns with WGS84 longitude and latitude to a table containing northings and eastings. The source data is Ordnance Survey's CodePoint Open, which I is ...
5
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How do I use GDAL to convert from an arbitrary projection/datum into Equirectangular/WGS84?

I've been trying to use GDAL to convert from an arbitrary projection/datum into Equirectangular (aka Plate Caree, aka Equidistant Cylindrical, aka Geographic, aka Lat/Long) with WGS84 datum. All of ...
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1answer
651 views

I have several layers (polylines and polygons) that are of the same area but they don't overlap in ArcMap as they should, what do I do?

For my GIS project for my class, I have downloaded several vector layers from different websites (polyline of the continental divide, a boundary polygon of New Mexico, a rivers and water bodies layer ...
5
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2answers
648 views

Why are the coordinates transformed with proj.4 off compared to http://valdemar.kms.dk/trf/?

I am trying to transform from epsg:4326 (wgs84) to epsg:25832 (utm ETRS89) using Proj.4. I am comparing the results with results from http://valdemar.kms.dk/trf/ . it seems like the results ...
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Is it possible to reproject spatial data using SQL Server?

SQL Server takes an SRID when creating spatial data, but is it possible to retrieve an object as a different spheroid? For example, let's say I have a bunch of spatial polygons using SRID 4258, but ...
3
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Which ESRI defined geographic transformation do I need to use to convert my “ NAD83 Northern Virginia” data into WGS 1984 Web Mercator?

My title pretty much tells it all.. I have a number of datasets in which I want to batch project from NAD83 Northern Virginia Datum into the correct Web Mercator projection.. When I do a straight ...
4
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1answer
396 views

what are the main advantages of using a Double Stereo projection?

I'm not per say a GIS guru, I'm more of a user of the technology. On a recent project we were asked to analyze, provide, and submit all our analysis using a Double Stereo projection. What are the main ...
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2answers
370 views

Positional changes bewteen MapInfo 7 and 10

I have just come across something bizarre and I can't explain it. I have programs for creating grid squares and for converting points to polygons based on an OS grid reference [GB BNG]. Recently we ...
4
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1answer
302 views

Is a WMS map always a constant scale?

If I get a map back from a WMS server is the scale always constant over them map regardless of the reference system? So if I have a map which is 100 pixels wide, will the point at 50 pixels always ...
5
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1answer
667 views

What is north-up projection?

How do I know what projection to use for north-up or 0 rotation? I have a gtiff (ND83-nf) that gives me the error when importing to Grass. Should I re-project or recreate the image with the rotation ...
2
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1answer
2k views

How can I convert from EUREF-FIN coords to Lat/Long?

See question title, how can I Translate EUREF-FIN coords to Lat Long?
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332 views

How does ESRI, and how should anyone, transform a coordinate that lies outside a grid transform (e.g. NADCON)?

As I understand it, a datum transform (e.g. urn:ogc:def:coordinateOperation:EPSG::1241) based on a grid interpolation method, e.g. NADCON, is undefined outside of the grid of points. Therefore the ...
5
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2answers
257 views

Arcmap: Create a projection to emphasize a given direction?

Suppose one had a dataset (centered on a given coordinate) of lines that were very close together in terms of longitude but also had important turns/bends far separated by latitude. In order to map ...
16
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8answers
456 views

Can you suggest some well-written introductory texts about coordinate system projections?

Even after some time working in this GIS field, I still don't have a solid understanding of spatial references, how they are projected, and most importantly, if you still need to worry about the fact ...
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3answers
442 views

Need help understanding why gdal projections aren't giving me what I expect?

When using gdaltranslate and gdalwarp I specify the following transfomation (in for GCP's and translate, out for warp) +proj=lcc +lat_1=40.03333333333333 +lat_2=38.73333333333333 +lat_0=38 ...