I need to find the "normal" latitude and longitude of a point in this format:
POINT (-8114244 4999772)
I tried using DBGeography.CreateFromPoint, but i think i used the wrong srid.
(i have searched before asking the question, but being numbers google is not very helpful).
Thank you
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I have a region table in oracle 12c, the table include 9 region that each of them defined by a polygon.
Polygon defined by 4 points in 2D.
I give a point from client and I must find out that this point is in which polygon. can anyone help me with this problem?
by the way I use Oracle 12c.
Ray casting algorithm is a popular solution to your problem https://en.wikipedia.org/wiki/Point_in_polygon. You can find pseudo-code easily and can start from that.
If you want to have solution in a specific language, then sorry I can't be of help.
I'm investigating about the best way to know what coordinates are around an specific coordinate.
I mean:
If am in the coordinate:
#29.817178,-95.4012915
How I can know if the coordinate: #30.00121, -93.13213 has 50km (or less) of my actual position?
You should use the Haversine formula, a good explanation can be found here with a javascript example.
Since you're dealing with latitude and longitude, you need to calculate the great circle distance between your two points.
The formula is a bit detailed so I won't reproduce it here, but it's explained in the above linked Wikipedia article.
I have a list of points with latitude and longitude coordinates, from which I want to enter a point say X. I need help coming up with an algorithm to determine the closest 3 list members to that point x.
You'll probably have to use the Haversine Formula. It calculates Great Circle distance between two points on the Earth's surface. Here's a good article explaining that, and here's an answer to a question similar to yours. Hope that helps!
See the method computeDistanceBetween() in the google.maps.geometry.spherical namespace:
https://developers.google.com/maps/documentation/javascript/reference#spherical
Then, here's an old V2 demo that uses Array.sort():
http://maps.forum.nu/gm_array_sort.html
You could combine the two, implementing
computeDistanceBetween() instead of compareDistance() as the sorting function.
Note that this is all done client side.
Is there a way to determine what will be the destination lat/long if I have the initial lat/long, and distance from start point to the end point, and a slope of 98 degree with respect to the x-axis.
This link: http://www.movable-type.co.uk/scripts/latlong.html has the formulas required.
I am sorry that I can't find a pre-built script. Perhaps someeone else knows of a script that will apply those formulas for you. However, with a bit of effort, you should be able to take those formulas and create your own script. (It is a hassle - but the script may not be reasonably simple to write if you do decide you need to do it yourself.)
I am in charge of a program that is used to create a set of nodes and paths for consumption by an autonomous ground vehicle. The program keeps track of the locations of all items in its map by indicating the item's position as being x meters north and y meters east of an origin point of 0,0. In the real world, the vehicle knows the location of the origin's lat and long, as it is determined by a dgps system and is accurate down to a couple centimeters. My program is ignorant of any lat long coordinates.
It is one of my goals to modify the program to keep track of lat long coords of items in addition to an origin point and items' x,y position in relation to that origin. At first blush, it seems that I am going to modify the program to allow the lat long coords of the origin to be passed in, and after that I desire that the program will automatically calculate the lat long of every item currently in a map. From what I've researched so far, I believe that I will need to figure out the math behind converting to lat long coords from a UTM like projection where I specify the origin points and meridians etc as opposed to whatever is defined already for UTM.
I've come to ask of you GIS programmers, am I on the right track? It seems to me like there is so much to wrap ones head around, and I'm not sure if the answer isn't something as simple as, "oh yea theres a conversion from meters to lat long, here"
Currently, due to the nature of DGPS, the system really doesn't need to care about locations more than oh, what... 40 km? radius away from the origin. Given this, and the fact that I need to make sure that the error on my coordinates is not greater than .5 meters, do I need anything more complex than a simple lat/long to meters conversion constant?
I'm knee deep in materials here. I could use some pointers about what concepts to research.
Thanks much!
Given a start point in lat/long and a distance and bearing, finding the end point is a geodesic calculation. There's a great summary of geodesic calculations and errors on the proj.4 website. They come to the conclusion that using a spherical model can get results for distance between points with at most 0.51% error. That, combined with a formula to translate between WGS-84 and ECEF (see the "LLA to ECEF" and "ECEF to LLA" sections, seems like it gets you what you need.
If you want to really get the errors nailed down by inverse projecting your flat map to WGS-84, proj.4 is a projection software package. It has source code, and comes with three command line utilities - proj, which converts to/from cartographic projection and cartesian data; cs2cs, which converts between different cartographic projections; and geod, which calculates geodesic relationships.
The USGS publishes a very comprehensive treatment of map projections.
I'd do a full-up calculation if you can. That way you'll always be as accurate as you can be.
If you happen to be using C++ the GDAL is a very good library.
For a range of 40km, you may find that approximating the world to a 2D flat surface may work, although a UTM transform would be the ideal way to go - in any case, I'd advocate using the actual WGS84 co-ordinates & ellipsoid for calculations such as great circle distance, or calculating bearings.
If you get bored, you could go down a similar line to something I've been working on, that can be used as a base class for differing datums such as OSGB36 or WGS84...