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21

Well, technically, NAD83 is not a subset of WGS84. If you mine further in the SpatialReference.org projetion definitions, you can see the difference between the two projections. PROJ.4 definiton of NAD83: +proj=longlat +ellps=GRS80 +datum=NAD83 +no_defs PROJ.4 definition of WGS84: +proj=longlat +ellps=WGS84 +datum=WGS84 +no_defs As you can see, the two ...


15

No, a datum and ellipsoid are not equivalent. For a loose definition, think of the ellipsoid as defining size and shape. The datum then fixes that ellipsoid to the earth. NAD83 (various realizations) and WGS (another set of realizations) use almost the same ellipsoid GRS80/WGS84, and were originally designed in the 1980s to be equivalent. Since then, NAD83 ...


12

Typically, NAD83 and WGS84 are within one meter of each other. Your concerns about differences of 2.5 feet, which are less than a meter, indicate you do need to perform this datum transformation. Briefly, this calculation requires knowledge of when the coordinates were collected so that their movement over time can be accounted for (primarily due to the ...


6

Short answer is yes. You need to convert from your coordinates' native reference frame to the NAD83 realization's reference frame, then possibly add an adjustment. In the case of NAD83(CSRS), which I use, there are 3 steps: Native RF -> ITRF96(1997.0) ITRF96 (1997.0) -> NAD83(CSRS) Grid shift Steps 1 and 2 require the Helmert transformation. Step 3 uses ...


5

You have an ESRI projection (ESRI:102719) however PostGIS (and everyone else but ESRI) are expecting EPSG:2264 (or possibly EPSG:3359 or EPSG:3632). You can use the ESRI one (just be aware that this will not interoperate well with others) - just run the following: INSERT into spatial_ref_sys (srid, auth_name, auth_srid, proj4text, srtext) values ( 9102719, ...


5

WGS 1984 has had several "releases". I'm not sure whether or not to call them re-adjustments. WGS 1984 is loosely tied to the International Terrestrial Reference Frame (ITRF), maintained by IERS. The first transformation, WGS_1984_(ITRF00)_To_NAD_1983, assumes that WGS 1984 is the one tied to ITRF00 and the NAD 1983 realization is CORS96 or similar. That ...


3

It's good practice to reproject, but not necessary, as ArcMap does reprojections on the fly. Reprojection does help to cut down on processing and server lag time, but in all cases it is not practical to reproject every time you add the layer to a map (webservices, dynamic datasets you receive from other agencies, etc). If you are in a situation where ...


3

Edit: Nevermind, I found the answer. I mistakenly thought (1) that you needed to have base map and the XY coordinates in the same projection and (2) needed to have them stored in the same distance units. This isn't the case..I'm still quite new to GIS. I fixed the solution simply by looking up the different State Plane Coordinate Systems for Missouri and ...


3

You may try to perform these steps: Create new QGIS blank project; Only load the shapefile which has the WGS84 as CRS; Right-click on the loaded layer from the Layers Panel and click on Save As... From the dialog, choose a name for the output layer and set the desired CRS; Create a new QGIS blank project and load both layers: they should be aligned. I ...


3

As long as everything is configured correctly on your GPS receiver, and it was clear skies, and there weren't any buildings obstructing your receiver, then I would say that the points you collected from your receiver are most likely in the correct spot. I am curious where you got this benchmark location from. Is it something you collected earlier? Is it data ...


3

Within the ArcGIS platform, each feature class (or all the feature classes within a feature dataset) may only have one SpatialReference. The coordinate system is one aspect of a SpatialReference (the others include a vertical coordsys, and the XY/Z/M origins, precisions, and tolerances which define basis for coordinate comparison). Coordinate systems can ...


3

If you check the official definition in the EPSG Geodetic Data Registry, it lists: Remarks: Used as part of NAD27 to/from WGS 84 transformation for offshore oil operations - see code 8647. Scope: Accuracy 1 to 2 metres. Used for oil industry operations only. Information Source: Various oil industry sources. The transformation parameter values are ...


2

Esri software does not have a built-in transformation to convert between NAD 1983 and NAD 1983 CSRS in Ontario. The Ontario Ministry of Natural Resources and Forestry provides an NTv2 file to convert between NAD 1983 (original) and NAD 1983 CSRS. You can download it from COSINE. You have to apply, but it's not onerous, and the NTv2 files are free to ...


2

I found that for a successful dxf export you must not enable 'on the fly' reprojection in order to have a project crs different from the data. The project has to have the same crs as your data. cp this issue: QGIS 2.14.3 export PostGIS layer to dxf issue two tickets are on the way concerning the same issues: https://hub.qgis.org/issues/14940 https://hub....


2

I'm an Alaskan GIS user. Familiar with datums up here. Roads from AKDOT, derived from 1:63,360 scale maps, treat as "NAD83" and continue to do so, accepting NONE for transforming to other forms of NAD83 in Arc when asked. Thats because +/ 40 meter data is not at same scale as modern transforms. As for 2007, forget about it. Don't worry about that ...


2

Update: I got in contact with GeoBC and they did have the NTv2 file I was looking for. Thank you!


2

If you are planning to perform spatial analysis using your data, I suggest you to reproject all your data into one projection, either using ArcGIS or FME. Sometimes the reprojections does not work perfectly on the first try, you may need to try a couple times to get it right.


2

I've solved my issue. Long story short, I was importing the wrong elevation model file. See, the elevation data with which I'm working is an ArcGIS grid, so several files work together to provide a meaningful elevation model in QGIS. (Forgive the triviality here, but this is new to me. In my case, I was importing dem_10.ovr, which appears coherent when alone ...


2

Here's What you have to do : Set ArcMAP to NAD83. Load your XY data. Export them to a Shapefile. Project your Shapefile to wgs84 using the "Project" tool in Data managements toolbox.


2

You might look into http://desktop.arcgis.com/en/arcmap/latest/map/projections/choosing-an-appropriate-transformation.htm Conversions between NAD83 and WGS84 are always done on lat-long coordinates. So you have to convert your Illinois coordinates from transverse mercator to NAD83 lat-long with the parameters you have got, then use the transformation from ...


2

When you use a GPS for creating and finding the point again it does not matter as errors balance themselves. But you need the accuracy for planning anything or plotting courses. Whenever you draw or calculate something in a GIS that you need to find in real world you stumble into this problem. WGS 84 is therefore not very accurate as it is a compromise for ...


2

Looking this projection up on epsg.io gives ESRI:102646, while digging around a bit gives EPSG:2230 which GeoServer will recognise: PROJCS["NAD83 / California zone 6 (ftUS)", GEOGCS["NAD83", DATUM["North_American_Datum_1983", SPHEROID["GRS 1980",6378137,298.257222101, AUTHORITY["EPSG","7019"]], TOWGS84[0,0,0,0,0,0,0], ...


2

This should generally work, but you'd have to combine transformations. In this case, convert from NAD83 to WGS84, then from WGS84 to NAD83 HARN. ArcMap selects these transformations automatically when you input your original and desired coordinate system. This is what it looks like for me: It runs without errors. As far as the accuracy, you will lose some. ...


2

If you are using Python (and do not want to install QGis), you can use pyproj module. The transform method converts between two coordinate systems.


2

The CRS of the King County parcel.shp is NOT NAD83. You see it from the extent which is obviously not degrees (what NAD83 uses), but meters or feet. It seems that ogrinfo knows which CRS the shapefile has (State Plane Washington North feet), so you better leave it that way. EPSG code would be EPSG:2926. The shapefile should import into QGIS correctly when ...


1

If you've access to ArcGIS, open a new map, add a 'basemap' from the server, with a known coordinate system, and then add your two data files. One or both of them will come in without a defined coordinate system. Then change the coordinate system on the MXD until they all line up properly. The one that works will be the coordinate system to assign to your ...


1

I've had to do something similar and opted to use the BLM GIS Rest Service. You can create a URL and the service will respond back with the coordinates. Unfortunately you can only send about 25 PLSS descriptions at a time due to the constraints of how long a URL can be. So, I created a list of URLs and used wget to batch process them. Here is an example ...


1

There is no formula/equation to convert from the PLSS to lat/lon. The PLSS is a reference grid, not a coordinate system (and note that it doesn't cover the entire US). To automate this, you would need to generate (or find - I don't know if one is out there) a coordinate lookup table for a script to reference or to use in a join. Your lookup table would need ...


1

You can send a text file to BLM for batch processing. http://www.geocommunicator.gov/Geocomm/lsis_home/townshipdecoder/index.htm


1

There is the paper "Transformations between NAD83 (2011) and WGS84 (G1674)" from the US NGS detailing the process of converting NAD83 data to WGS84 data.


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