Tagged Questions

The coordinate system known as World Geodetic System 1984 (EPSG:4636)

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23 views

Point-in-polygon using WGS84 geographic coordinate system

When running a point-in-polygon operation, is it valid to run that with polygon features in straight up WGS84 and a point in lat/lng, or should both be projected into a non degree based coordinate ...
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1answer
26 views

J2000 to WGS84 in QGIS?

How to transform Earth-Centered Inertial J2000 CRS to WGS84 CRS in QGIS? I searched J2000 in spatialreference.org, however nothing found. I don't know the proj4 string of J2000. Any advice would be ...
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0answers
29 views

Conflicting WGS84 coordinates between Trimble and Garmin GPS receivers

I am a contractor at a government facility in Nevada. We have our own in-house survey department who, for a number of reasons, still uses NAD27 State Plane Coordinates (Nevada Central Zone 2702) in ...
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2answers
41 views

Is there an algorithm for transforming from CGCS2000 to WGS84?

Is there an algorithm that supports transforming from CGCS2000 coordinate to WGS84 coordinate? CGCS2000 is China Geodetic Coordinate System 2000. Any advice would be thankful!
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1answer
36 views

Transforming coordinates between wgs84 and UTM ED50 31N, what am I missing?

My problem is I must tranform a point cloud from wgs84 (geographic) to UTM (projected) ED50 for zone 31North. Easy, isn't it? Well, first surprise is I have several free webs who offer me this ...
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1answer
65 views

Convert EPSG:3068 to WGS84

So I have a GeoJSON with EPSG:3068 and I would like to convert the coordinates to WGS84(EPSG:4326). I could also convert them before I write them to GeoJSON. I could not find an algorithm for the ...
3
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1answer
75 views

How to convert the SRTM DEM orthometric to ellipsoidal heights using ArcGIS or others GIS?

Recently I got the SRTM DEM from Cgiar,which based on WGS84/EGM96. and I merged the tiles to one tiff file. I want to get the WGS84 ellipsoidal heights. According the steps from the Arcgis Help 10.2 ...
3
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1answer
59 views

Need advice for localized survey base point

I have a set of 4 control points used for H and V localization. There is a base point located far to the SW of the property. I did not create this myself, but took it off of an existing Pocket 3-D ...
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1answer
47 views

PostGIS get geometries within a radius of n meters using WGS84 [duplicate]

select * from zones z where st_intersects(z.geom, st_Buffer(ST_SetSRID(ST_Point(2.336031, 48.863172), 3857),1)); It looks like the 1 in the st_buffer is being interpreted as degrees, I need to find ...
3
votes
2answers
118 views

Merge geojson polygons with WGS84 coordinate

I have a Geojson file with some adjacent polygons and I want to merge them into one. I know it's a recurrent question but I can't find information for polygons with latitude and longitude coordinates ...
0
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1answer
26 views

Getting WGS84 height of a given place mark - Google Earth

Setting manually a place mark for a given location or obtaining the coordinates via Google Earth search yields the (Long,Lat) WGS84 coordinates. I'm fully aware of map is a 2D concept, yet is there a ...
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1answer
77 views

Proj4js Problem in converting coordinates from google mercator

I am a really beginner into web-cartography, so sorry if this subject is rudimentary or basic but I truly search for a long time and I am still stick in it. So the problem is: I don't understand why ...
2
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0answers
59 views

Returning distances in meters from Near (Analysis) tool of ArcGIS for Desktop?

I'm trying to write a python program that returns the distance from each point in a set to the nearest road. Specifically, I was looking for any points within 10 meters of the roads. Both sets of ...
2
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0answers
64 views

Google Earth / QGIS projection (great circle line)

Here is my question: 1- Based on a long distance segment ( approx 2000 km) drawn on Google Earth and imported as shapefile in QGIS I want to obtain a terrain profile based on "Terrain Profile" ...
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0answers
29 views

convert headerless flat binary files to tif

I have set of headerless flat binary files (those are out put files of TIMESAT software). I want to convert those to .tif format. I did it using ENVI. but it does not overlap with the original input ...
1
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1answer
42 views

Problem with projection of Slovenian Shapefile in QGIS

I hope someone can help me for this: I'm doing my masters thesis in Slovenia (in the field of wildlife management), for this I got a Shapefile of slovenian data by the University. As a main layer, I ...
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0answers
23 views

Pros and Cons of a latitude adjustment grid vs other methods of area calculations

When working with high resolution global raster data in WGS 1984 I often need to calculate areas. Now the traditional way for me to achieve this has been to reproject the data to an equal area ...
4
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1answer
74 views

Should geometries be drawn using rhumb-line or great-circle paths?

I work with WGS-84 coordinates and, most of the time, my map display (luciadmap) is in Mercator projection. My client is surprised to see that, for a rectangular geometry: the line between the 2 ...
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1answer
59 views

The ratio Pixel distance to geographical distance?

I have had this problem for several days and I have no idea to solve it. The problem is that I am trying to find out the length and width of ships from a Bing map. I got the location point (lon, ...
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0answers
32 views

Node.js transformation from NAD83 to WGS84

I've used the excellent npm shapefile library to import Canadian electoral districts into MongoDB. Here's a sample file: http://ftp2.cits.rncan.gc.ca/pub/geott/electoral/2011/fed308.2011.zip Is ...
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0answers
34 views

Is there a method to tell which hemisphere a point belongs to, in WGS84 geoid, where the equator is an arbitrary ellipsis?

I use the WGS84 geoid (because I'm working with a GPS chip). I define an ellipsis that splits the surface in two parts, lets name these 'A' and 'B'. This ellipsis is defined by two points 'a' and ...
2
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1answer
131 views

Updating and exporting XY positions in UTM and WGS84 to spreadsheet using ArcGIS ModelBuilder?

On a daily basis I'm editing the geographic positions of various points of a shapefile (corner_XY.shp) by dragging them on my map. When this editing task is done I'm updating the points coordinates in ...
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2answers
67 views

Projected coordinate system for South America

Does anybody have any suggestions for a projected coordinate system for the Northern part of South America? I have a data set that reaches from Venezuela to Southern Peru and I'd like to do some ...
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0answers
48 views

My map is little bit off

I am pretty new in GIS things and i have been learning how to use QGIS. Most of the maps are fine, but yesterday I went to GIS center at my University and I got the maps of my country that I will be ...
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1answer
100 views

Converting WGS84 points to a 2D x,y point (plotting)

I have been trying to convert the WGS84 style geo-positions to x,y coordinates on a 2D plane. I have looked into many different links, websites, studies and I honestly gave up on finding a plane copy ...
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2answers
51 views

Help projecting Austria data with QGIS

I'm trying to reproject this dataset from Austria Statistik Geodata. Data comes in "MGI_Austria_Lambert", and I'm trying to reproject to WGS84 What I'm doing is Saving layer as... and selecting ...
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0answers
19 views

Setting correct units for Near tool?

I need to use the near tool to calculate distances between data points and a stretch of coastline. My problem is that when I run the function, the values that come up in the Field of the points' ...
3
votes
2answers
89 views

Google layers not matching

I'm working in a project with whole Europe data. I'm working with WGS84 (4326), and sometimes I overlay my polygons with Google maps layer (in QGIS) to see some details. When I do this, I have to ...
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1answer
51 views

Unable to save to in Geojson format with the correct projection

I have a shape file (Polygon) in Qgis that I wish to save in Geojson in order to display it with the mapbox javascript api. Original projection is in POSGAR 97 My issue is that it does not reproject ...
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2answers
60 views

Shape length distance wrong in Robinson projection

I have a world map in the WGS 1984 Geographical Coordinate System. I want to measure the lengths of borders between countries in kilometers. To get the units in meters, I have first used the Define ...
3
votes
1answer
109 views

Comparing printed nautical charts to GPS coordinates

I'm just getting my head wrapped around the various geodesic systems. I have some (printed) Finnish nautical charts I'm trying to match to GPS coordinates. Given the number of underwater obstacles, ...
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0answers
71 views

SRTM elevation data question

I have a question concerning the SRTM elevation data (http://srtm.usgs.gov/). As a little thought experiment, assume I want to build a 3D model of the earth's surface as a point cloud. The earth's ...
2
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1answer
30 views

Figuring out what coordinates supposedly using 'NAD31 projection' refer to

I'm working with a GeoJSON file that contains sets of coordinates associated with street corners in the city of Montreal, Canada. The spec sheet of the API delivering those GeoJSON specifies that the ...
2
votes
1answer
95 views

Extracting data from Natural Earth using GeoTools java class?

I wrote a small java class to extract country boundaries from naturalearthdata.com data. My problem is that the coordinates do not match with OSM map, the whole polygon is shifted... e.g. according to ...
0
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1answer
110 views

Raster and vector layer in the same CRS don't match

While adding multiple raster and vector layers (and setting them all in CRS WGS84) in QGIS 2.2, they don't seem to overlap. Interestingly enough, only raster files overlap between each other, the same ...
0
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1answer
249 views

ArcGIS Conversion Error While Converting ED50 Datum to WGS84 Datum

With ArcGIS for Desktop, I tried a datum conversion of Transverse Mercator ED50 Datum to Transverse Mercator WGS84 Datum. Normally, the difference between two projections is approximately 180 meters ...
2
votes
1answer
464 views

Converting GPS Positions to Google Maps

I have a set of GPS-coordinates in a database, which I want to compare to a coordinate supplied by the html5 location API. My coordinates look like this: <WGS84Coordinates> ...
2
votes
3answers
88 views

Mis-aligned shapefiles

I'm a beginner at QGIS and I'm having trouble aligning my shapefiles. I have two datasets: one originally in WGS84 (lat/long) and another in Corrego Alegre/UTM zone 24S. I need to convert the second ...
0
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1answer
32 views

QGIS “transform error” after downloading from OpenStreetMap

Beginner's question. I am working on this tutorial: http://www.qgis.org/en/docs/training_manual/vector_analysis/basic_analysis.html After selecting WGS84 UTM zone 34S in Project Properties, I receive ...
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1answer
140 views

How to draw an arc by centerpoint, radius and azimuth in KML

The question is how to generate lon/lat coordinates for an arc/sector. Coordinates can be used/filled into a KML file. Pointers to geometric formula or a program applying the formula are much ...
2
votes
1answer
51 views

Why this two datasets don't match?

I have a postGIS database in SRS 4326 (WGS84) with several Europe layers working well, but when I load a shapefile projected to the same SRS with QGIS, the layers don't match. To explain it better ...
2
votes
1answer
312 views

Geographic Transformations in Alaska Between NAD83 and WGS84

I have done a ton of research on the most accurate transformation to use in mainland Alaska to convert between the NAD83 and WGS84 datums, but I just can't seem to find a definitive answer. ArcMap ...
2
votes
1answer
136 views

How do I convert Eastings and Northings projection to WSG84 in geopandas?

I'm very new to projections and struggling to convert a map dataset from OSGB36 (Eastings and Northings) to WGS84 (lat/longs). I've used geopandas to import a shapefile. Now I want to export it as ...
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2answers
294 views

How do you convert SRTM HGT elevations from WGS84 into meters above sea level?

I am building a JavaScript script that reads binary HGT files - as generated by the SRTM - and converts the data into bitmaps viewable in your browser. You can try out the script and view the source ...
4
votes
0answers
151 views

GeoJSON shape distorted on Leaflet.js spherical mercator WMS map [closed]

I have a map with a simple WMS layer in spherical mercator projection (rendered by a OSM-Mapnik-TileCache server stack, everything is in EPSG:900913 / EPSG:3857). First: I can't understand why, if ...
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vote
1answer
47 views

OpenLayers Projection and Datum Question

I had a conversation with a co worker that was asking about an OL map I am developing. She asked me what the 'projection' was and I said EPSG:4326. She didn't know what that means, so I said it's ...
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1answer
92 views

Why do MGI and WGS 84 data not line up in ArcGIS for Desktop?

When i reproject raster from MGI 6 zone to the WGS84 it makes a mistake (it is moved for 380 m )See example below: I know that the problem is in MGI 6 projection (it is not accurate),but I do not ...
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1answer
148 views

Problem with import CSV files to QGIS 2.0.1

I have a problem with import CSV files to QGIS 2.0.1. I have a file with WGS84 coordinates it looks that: Nr;Longitude;Latitude 1;18,06,23.66;54,83,12.50 2;18,08,81.30;54,73,09.30 ...
2
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0answers
52 views

Re-projecting WGS84 to OSGB in SAGAGIS

I took some points with a GPS, and I'm trying to convert from GCS to OSGB 1936 British National Grid in SAGAGIS. I'm working with a shapefile. To reproject the vector layer to the OSGB projection I ...
2
votes
2answers
124 views

Problems with transformations in ArcMap

I have files projected in British National Grid. After I have transformed them into WGS_1984. I noticed that if I were to transform them back to BNG the original would not match the new. Is there a ...