I have a field site. I know the coordinates of the center of the field site and that the site is 350 meters by 500 meters. Is there a formula or program that I can use to find the coordinates of the borders of my site? Most of what I've found is not accurate enough for my purposes. Thank you for any help!
Convert your coordinates to a UTM (simple arithmetic transformation)
Convert to lat/long:
Here is open-source JavaScript code (link to github in article):
https://www.movable-type.co.uk/scripts/latlong-utm-mgrs.html
Related
I have a list with nearly 100,000 GPS coordinates in lat/long format in a CSV file. A lot of these are only a few inches away from each other, so I would like to merge them somehow, or filter those out that are too close together within a certain radius.
Do you guys know of a script or a service that can do this automatically?
There is a reference to a nice paper that explains how to find nearest lat/lng points inside a specified bounding box in another thread, which you can find here: latitude/longitude find nearest latitude/longitude - complex sql or complex calculation
Here is the direct link to the paper: Geo Distance Search with MySQL
I think you can adapt the idea from the paper to your domain in order to set up a filter procedure.
Recently I am working to plot latitude and longitude of GPS data on Google Map. The latitude and longitude is in NMEA format and I have converted it in to compatible format to display on google map. I am able to plot the data on google map successfully. My data is supposed to be on a straight line but it goes zigzag like mountains. Is is the problem of GPS data not having accurate latitude and longitude? or the problem while converting the NMEA format data? How to fix these kinds of errors if the GPS data is not 100% accurate?
Thank you.
Depending on the quality of your GPS receiver (recreational, professional, survey, military, etc), the accuracy of your GPS solution can be different. Some receivers can track more GPS signals at different frequencies, and can have an access to DGPS information, etc.
For recreational GPS receivers the error level can be at the order of 10 meters. So my suggestion is if you know that uour solution is a straight line, you can do a least square parameter estimation to a linear function. That approach tend to smooth out error and you can get better solution.
I am trying to properly project Latitude and Longitude into cartesian coordinates so that I can use an unscented Kalman filter to smooth out some GPS data. I am using constant jerk newtonian motion as my state transfer matrix. My issue is that I have tried many popular projections(Mercator, etc.) and when I reproject into latitude and longitude, my data is stretched with respect to maps. Any insight on my situation would be greatly appreciated! If you need more information please ask in the comments. Thank you.
The stretch factor between longitude and latitude is cos(latitude).
So you can do a local Cyclindrical Equidistant transformation.
this is a simple tranformation, but is only acurate around 10-100km
of the center (longitudeCenter, latitudCenter). this kind of projektion needs a (fixed) center.
Look further for "Cyclindrical Equidistant Projection" to get the simple formula.
So, I've got some data that has longitude and latitude. I don't know what projection those are from. I've got some latitude and longitude I'll be fetching from Google maps API, which uses a projection with SRID of 3857.
If I just assume the data is from the same projection, and it turns out they're not, how far off could my distances be?
For instance, if they're from a 3-d projection (say 4326), but I just put them into a Geometry column with SRID 3857, and we're in the Northern Hemisphere, (Great Lakes area, but also other parts of the US), is there a way I can figure out how far off that would be?
EPSG:3857 uses meters as units, while EPSG:4326 uses degrees. If you try to plot them on the same map without reprojecting one or the other, they will be very far off (many orders of magnitude) from each other.
You said you'll be fetching lat-lng from the Google Maps API, using a EPSG:3857 as a projection, but latitude and longitude coordinates are not projected by definition, although they may use a different datum. I can't find official Google documentation, but consensus seems to be that Google Maps API uses WGS84, same as EPSG:4326, so lat-lngs you pull from google maps API will probably fit exactly on top of others from EPSG:4326.
See http://spatialreference.org/ref/epsg/4326/ and http://spatialreference.org/ref/sr-org/7483/ and https://gis.stackexchange.com/questions/34276/whats-the-difference-between-epsg4326-and-epsg900913
I would like to be more specific about what I want to do. I get coordinates in ECI and I need to get the latitude and longitude from this. How can I do? I was searching but I could'nt find anything about it. Thanks again.
(I'm doing a small program in java that shows the position of a satellite in a given time. So, I used the NORAD SGP algorithm, and I have the position (x,y,z) and velocity(Vx,Vy,Vz). But the coordinates system used by this algorithm is the ECI, according what I read. Now I need to draw the satellite in a map, but I can't convert this coordinates to some system that could help me. I think if I can convert it to longitude and latitude it would be easy to draw. Could you help me? how can I do it? What is the best option(UTM,etc)? Thanks.)
What you want to do is called ECI/ECEF (cartessian) to Geodetic (lat/lon) conversion. This conversion is the most complex of all the geodetic conversions as the closed form solution is complicated. See page 34 of Stevens and Lewis, Aircraft Control and Simulation for a discussion of the coordinate systems: http://books.google.com/books/about/Aircraft_control_and_simulation.html?id=T0Ux6av4btIC
ECI to geodetic is a two step process:
The first step is the easiest in that you need to convert ECI (earth centered inertial) to ECEF (earth centered/earth fixed).
The second step is to convert ECEF to geodetic. You can read about solving this via Newton-Ralphson here: http://en.wikipedia.org/wiki/Geodetic_system
However, if I remember correctly, Newton-Raphson becomes unstable around the poles. The closed form solutions are much more complicated. I have successfully implemented Zhu's method. The advantage of the closed form solution is no iterations and there are no singularities (technically there are singularities but not above the earth). The reference: J. Zhu. Conversion of earth-centered earth-fixed coordinates to geodetic coordinates. Technical Report IEEE Log NO. T-AES/30/3/1666, IEEE, December 1993.
The PyMap3D library for Python has the eci2ecef and the ecef2geodetic functions. They interface with Astropy by default and are quite good, thanks to the hard work of Michael Hirsch (SciVision - he accepts donations).
You need, of course, to know the times at which the ECI coordinates were observed; without that you cannot convert them to ECEF. I recommend not using the simpler eci2geodetic function unless high precision and accuracy are not required; it will be somewhat quicker because it does not account for Earth's nutation, etc.).