Linked Questions

13
votes
2answers
16k views

Understanding terms in Length of Degree formula?

Online calculators such as http://www.csgnetwork.com/degreelenllavcalc.html (view page source) use the below formulas to get meters per degree. I understand in general how distance per degree varies ...
1
vote
3answers
3k views

Approximate distance between two points (longitude / latitude) without Haversine

How can I judge from the long/lat coordinates of a point A alone whether it is possibly/certainly not within a short distance of x meters from another coordinate B, using R (without applying geosphere:...
2
votes
1answer
3k views

How much error should occur when using WGS84 to ECEF coordinates?

The method is not recommended for distances larger than 4km. I am getting reasonable accuracy in terms of the east and north bearings, but for the up direction I am getting error upwards of 1km for ...
9
votes
1answer
987 views

Extracting values at specific latitude,longitude from MODIS swath data

I am trying to determine the amount of precipitable water vapor (PWV), ozone and aerosols as a function of time over specific spots on the Earth, namely our astronomical observatories. To do this, I'...
1
vote
1answer
1k views

Rotating a set of coordinates around a point

Based on the user's location I want to draw a circle that passes a given coordinate X (so the radius will be the distance from the user location to X). Based on this https://smilebasicsource.com/...
0
votes
1answer
408 views

QGIS heatmap issue

I'm trying to create a heatmap on QGIS 3 from a layer based on a 20,000-entry CSV file with longitude and latitude values, using EPSG:4326 as the CRS. The layer itself looks fine, the markers are ...
2
votes
0answers
906 views

Creating fishnet using Python?

I am trying to create a fishnet of x by x miles for all USA, same as this basically: http://www.giscourse.com/creating-a-fishnet-grid-using-arcgis-10/ However, I want to do this with python. My ...
2
votes
2answers
248 views

Getting lat/lng of an object X inches from the GPS? [duplicate]

I'm working on a project where I have a GPS and two receivers to create a triangle with a transmitter. The problem I'm trying to figure out right now is how can I get the position of the two receivers?...
1
vote
1answer
197 views

PostGIS creating an envelope around a buffer returns strange results

For a spatial search I need a 900km buffer around a given point(lon 18 degrees, lat 63 degrees) and search all geometries in a table that intersect with the envelope around the buffer( actually a ...
1
vote
1answer
156 views

Calculate Circle Geometry Based On Point for Map Service

I have a Map Service that is currently just multiple boundary layers. Users query this Map Service with a lat/long to determine whether or not a Point falls within a Boundary. Currently they are using ...
0
votes
1answer
103 views

plotting a circle in a spreadsheet

I can't get my head around plotting a circle on a big sphere (Planet Earth). I have a column that has 180 rows - 1 for each degree. The next row is each degree converted to radians. Easy so far. A1 ...
1
vote
1answer
40 views

0.5° × 0.5° to meters

This paper https://www.sciencedirect.com/science/article/pii/S1352231017300936 mentions using a 0.5° × 0.5° resolution grid, and I've tried googling to find out what that means in meters but I come ...