A reference framework consisting of a set of points, lines, and/or surfaces, and a set of rules, used to define the positions of points in space in either two or three dimensions.

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6k views

What is the relationship between ITRF and WGS84?

Why are there people saying that "I am using WGS84(ITRF96)"? There are newer version of ITRF. Will WGS84 follow it? If so, what will be the influence to us?
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1answer
359 views

extracting pixel value from a table in postgresql

I have a table in postgresql that contains ID, row number, column number, pixel value and centroid of the pixel in WGS84 lat-lon system(4326). How could I extract the pixel value by giving a point in ...
4
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1answer
525 views

How to specify coordinate reference system (CRS) for scalebar that is different to project CRS?

Is it possible to specify a coordinate reference system (CRS) for the scalebar that is different to the project CRS? For example, my project CRS uses geographic coordinates (lat/long), the reason ...
4
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1answer
502 views

EPSG operations and operation methods

Querying through the EPSG database, I can see the tables epsg_coordoperation where transforms and conversions between different CRS are stored, and epsg_coordoperationmethod which stores the ...
4
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1answer
3k views

Convert Gauss-Kruger to UTM

How to covert Gauss-Kruger coordinates to UTM coordinates with GeoTools java library? As I have figured out the location (zone, country) is important. I need the calculation for Slovenia.
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1answer
43 views

How to use Prolong Line feature with an input layer in WGS84?

I have a source point table in SRID:4326, and to make it look geographically accurate, I project my project file to SRID:2877 (State Plane CO) (layer still reports source CRS of SRID:4326). In order ...
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1answer
155 views

How do I find/define a projection that gives me exact relative positions inside an area?

Assuming that a set of positions are all inside a 5km square area: How do I find/define a projection to reproject the positions, so that the relative positions between the now reprojected positions ...
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2answers
1k views

Difference between latitude and longitude

It occurred to me that latitude and longitude are not homologous in that the lines of latitude lie on parallel planes or slices through Earth, while lines of longitude are not parallel and meet at the ...
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1answer
404 views

How to manually add spatial reference information for FEWS rainfall data in ArcMap?

I am trying to match rainfall data from USGS/FEWS to coordinate locations of survey households in Uganda, so I will need to be able to project the rainfall data. So far, I downloaded the dekadal RFE ...
4
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1answer
272 views

QGIS “ERROR 6: No translation for Lambert_Conformal_Conic to PROJ.4 format is known.”

I am trying to clip a county DEM file using the PLSS Section shape files as mask layers... that is, I want it clipped to sections so that I can load my DEM into QGIS one section at a time, without ...
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1answer
119 views

proj.4 definition for (obsolete) UK War Office “Italy South” grid

I'm helping a friend convert his late father's war diary coordinates to WGS84. I have a proj.4 definition that appears to work in QGIS, but if I transform a scanned map with gdalwarp, it's not even ...
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1answer
1k views

In ArcObjects, how do I change the spatial reference of a Map (Data Frame) in an existing MXD?

I need to change the spatial reference of an existing MXD programmatically. In ArcMap UI, I would take the following steps: 1) Open the data frame properties and go to the Coordinate System tab; 2) ...
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1answer
188 views

Problem with custom projection definition in Qgis

I want to define a custom crs valid for Mexico. The context is that older cartography in Mexico is based on the NAD27 datum. I wanted to test the following proj4 string +proj=longlat +ellps=clrk66 ...
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1answer
398 views

NAD83 and NAD83 State Plane

I'm struggling with a projection question. I have some data in California State Plane and am trying to align a NED with NAD83. I thought these would just natively align, but they don't seem to ...
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2answers
1k views

Create custom projection using either QGIS (or ArcGIS Desktop)?

I have searched for an answer to this but don't see anything relating to what I am trying to do. What I have are a series of Geographic Coordinates, Latitude, Longitude, Ellipsoid heights. What I ...
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1answer
669 views

How to define a CRS using a projection rotated about a given point

I have a data set that uses a common projection, but has its own false easting and northing, and is rotated 315 degrees. I need to be able to work in this CRS and easily translate from one CRS to ...
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2answers
110 views

Merging rasters in QGIS?

I have 3 modis tiles that I want to merge together. They were all reprojected in the same CRS (from sinusoidal to WGS84 UTM zone 32 N), but I cannot succeed. I have tried with merge and virtual ...
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1answer
654 views

What's the correct way to reproject a population raster?

I'm working with a population raster that is in the WGS84 coordinate system, and I want to get it into a projected coordinate system (Albers Equal Area), using ArcGIS 10.1. According to the metadata, ...
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2answers
3k views

What formula is used for distance between 2 points in Google Maps?

What formula is used by Google Maps for calculating the shortest distance between 2 points (having their Lat, Lng coordinates)? Is it purely based on Haversine? Or is it something different? Is there ...
4
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1answer
248 views

How to change the settings for where ArcGIS splits world data

I have a world map made up of 6 shp files. All the files and the data frame are set to WGS84. The way Arc 10 and 10.1 decides to display the files, it splits Russia into 2. The majority of Russia ...
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1answer
1k views

How to delete coordinate system from raster file with prj.adf?

How can I delete the coordinate system from a raster file like .adf which is multiple files? I found a file with tha name "prj.adf" so if I delete this file is it enough? In shapefiles usually Ι ...
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2answers
341 views

geocoding addresses specifically into NAD1983 or converting X,Y into 1983 after geocoding

I'm going bananas trying to geocode addresses into a NAD1983. I have ArcMap 10.1 and I'm using the default address locator (North American 10.0 from arcgis online). No matter how low I set the ...
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1answer
321 views

Projecting gps data to get length of resulting line shape in ArcMap 10.0

I have gps data in WGS84 geographic coordinates. I will use the gps data to build a line shape in ArcMap 10.0. The data falls in UTM 15N. To get most accurate length of line, should I project the ...
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1answer
68 views

convert lat/lng to pixel and vice versa

This had been asked previously on Stack Overflow. I've tried different methods/formulas but results are not correct. 40.764296,-73.97302 should result into 930,3590 pixel on map image. I've Manhattan ...
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0answers
37 views

How to interpolate within defined boundaries of a deformed mesh using R?

My goal is to create an interpolation map of some output model results that are mapped on a deformed mesh (from a numerical simulation). The model results are in an x-y plane (representing ...
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1answer
41 views

Can Irish points be accurately represented by British OS Grid references?

I'm currently working in a database which stores mainland British locations as their Ordinance Survey Northing/Easting values. Can points in Ireland (primarily Northern Ireland) be accurately ...
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0answers
182 views

What projection system is used in China which is aligned with WGS84 [closed]

I have some GPS tracks in Beijing. I want to project it and convert the lat long degree values in meters for calculation in euclidian space. I was wondering what is the most suitable coordinate and ...
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0answers
316 views

Can GeoTools parse GML CRS definitions?

A kind of branching of this question. Soon I will need to handle GML Coordinate Reference Sysyem definitions in a Java servlet. Links: GML OGC reference. Concrete example. I know that GeoTools ...
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2answers
474 views

What coordinate NOTATION would this be?

0558253.7 13083091W The data came in a csv file which was then converted to an xlsx file in Excel. No mention of original coordinate system, and the fields were just named - "LATITUDE" and ...
3
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2answers
2k views

What is the process to calculate Helmert parameters?

I have some double points (the same points in 2 different datums). I'd like to calculate the Helmert parameters but I don't understand how. NOTE: I don't need software. I need an algorithm in order ...
3
votes
1answer
700 views

Arcobjects: Is my spatial reference Geographic or Projected?

I have the user select a coordinate system with the Spatial Reference Dialog. Is there a simple way to determine if the resulting spatial reference is a Projected or Geographic CS? I would of ...
3
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1answer
407 views

How to find out coordinate system to use pre-1940 Soviet map as raster

I am trying to use this map as a raster but I am not having any success in QGIS. I tried in Georeferencer to open raster and used these settings: Transformation: Thin plate spine Resampling Method: ...
3
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2answers
925 views

What kind of coordinate system is this?

I have a csv with a list of the world sea ports and their coordinates. The coordinates are in this format: 5234N 00226W How can i convert this to decimal Latitude / Longitude ? Data source
3
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1answer
583 views

Why are the formats of these coordinates different?

I'm really sorry if this is a silly question (and I'm sure it is) but I have tried searching but I am a complete newbie to coordinates and maps and I don't know what I'm looking for so am not finding ...
3
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2answers
57 views

Generic term for CRS axes?

We're making a light web front to a database, and I saw this in a test screenshot: Despite those coordinates being nowhere near North America, the "latitude/longitude" label for those coordinates ...
3
votes
1answer
220 views

Why not measure elevation from the center of the earth?

In trying to understand Geoid vs Ellipsoid height, I ran across this page. One of the claims is: Zero elevation as defined by Spain is not the same zero elevation defined by Canada ...
3
votes
2answers
5k views

Meridian convergence. True north, magnetic north and grid north

I'm having difficulty wrapping my mind around meridian convergence, the horizontal angular distance between true north and grid north. Say I want to determine if a feature lies to the east or west ...
3
votes
4answers
287 views

How to measure without coordinates?

My current Project is to "map" a turntable in qgis. I know, very unlikely but that's what my teacher wants. My teacher also wants me to measure something in this project (Very specific, isn't it?). ...
3
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4answers
11k views

Change number of decimal digits for features in ArcGIS 10?

I am editing vertices in polygons and points in ArcMap 10, and realised that they only hold 3 decimal digits for the X, Y coordinates, but I would like at least 6 decimal digits. Even if I type in ...
3
votes
2answers
70 views

What kind of projection is this?

Can someone tell me what the projection is in this zone map from NOAA? Addendum: I am trying to replicate it (or get close) in QGIS. I know very little about GIS, but I need to do this for a web ...
3
votes
3answers
2k views

Which projection is best for mapping the contiguous United States?

If I wanted to project latitude & longitude data for the contiguous United States (the United States excluding Alaska and Hawaii), which projection would I use? I prefer more accurate distances ...
3
votes
1answer
166 views

New coordinate system?

I just had my mind blown in answer to my previous question. I was going to rework that question, but decided it makes more sense to ask a new one. I had been converting between ECEF and lat/lon, and ...
3
votes
4answers
1k views

Why do area calculations return negative values?

I have created a shapefile with some polygons and am now trying to calculate the area of these polygons. The original CRS was WGS84, I have reprojected it to WGS 84 / World Mercator so unit is metres. ...
3
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1answer
482 views

How to programmatically determine whether a spatial reference factory code is valid?

I am using the following code segment to create a spatial reference. spatialReferance = arcpy.SpatialReference() spatialReferance.factoryCode = spatialReferanceFactoryCode ...
3
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1answer
102 views

Difference between datum and ellipsoid for geodetic coordinates?

Looking at the Wikipedia page for the North American Datum, it seems to imply that the datum is completely defined by the ellipsoid, which defines the major/semi-major axes, flattening, etc. For ...
3
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1answer
125 views

Converting coordinates in Florida, USA?

I have an point location and the information given is: Easting: 519122.06 Northing: 1290630.07 Original thought was it's UTM, but does not appear to be correct because I know the point needs to be ...
3
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2answers
119 views

Which SRIDs to use for what tasks?

I try to understand the idea behind the different Spatial Reference Identifiers. I understand that the different SRIDs identify different projection views on the earth and that they are important for ...
3
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1answer
111 views

Is it possible to define a custom CRS for a shapefile in QGIS that uses hundredths of a US foot?

I have several polygon shapefiles whose coordinates are defined as 100x their original coordinates projected from the Washington State South HARN State Plane in us-ft (EPSG 2927). I would imagine the ...
3
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1answer
142 views

Obtaining length of non projected feature (gcs_wgs_84) in meters instead of decimal degrees?

I could not find a post which answered to my problem and I hope I didn't miss it, in case I did I apologize. I'm working with Arcgis 10 and I have a multiple lines feature with gcs_wgs_1984 ...
3
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2answers
273 views

Can't find correct coordinate system: UTM83 Zone 15 forcing input in meters; need it to be read in feet

Forgive me, I'm a CAD person, and am very new to GIS. I've searched google and this site extensively for an answer, with no luck. My problem is that I was given a large number of sistered Raster ...