I was reading about the ethereum address generation process. I am very confused that when Private key generated is processed under "Elliptic Curve Digital Signature Algorithm" , we get a public key which is a point on graph. We take x & y co-ordinate of that point. Below is a sample of such process
Image showing x & y co-ordinate
I am not able to understand is how can we have alphabets in the co-ordinates. I think it should have only numbers. I know that public key is denoted in hexadecimal format but how come co-ordinates have alphabets in it . Can anyone please explain it to me.
Thank You
The x and y coordinates are also represented in hexadecimal. For example:
(b8b, 24f) (hex) = (2955, 591) (decimal)
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I'm working on Google maps which will show multiple vehicles. I've two points(one point which will be the old position and other will be the present position) this positioning system will help write an equation of a line passing through these two points. Which might intersect with other line and inform me about the probability of collision.
But the problem is that I'm fetching the coordinates from the GPS module and it will give the location in Latitude and Longitude format.
I'll need x, y coordinates for this writing the equation of the line passing through them. I've already explored most of the method in different web pages, but the problem is that they will ask for some screen size(or map bounds) which are kind of not compatible with my type of method.
Questions: What is the method to convert Latitude and Longitude to (x, y) coordinates, just like if we see from the space and earth was flat and taking Gulf of Guinea (Lat: 0°, Lon: 0°) as the origin.
If your task requires high accuracy you have to use Latitude/Longitude and to solve Great Circle intersection task. The Earth is not flat.
If you can accept existence of some error in your calculations AND all of your vehicles are located in small limited area (up to 100km, although it depends on error you can accept) you may assume this confined area as flat.
For instance, if one your vehicle is located at N10.0 E10.0, second one is located at N10.1 E10.2, you may choose N10.0 E10.0 as the origin.
As a result, these two vehicles will have the following (X, Y) coords (it assumes that axis X goes along equator):
1) (0.0km 0.0km)
2) (21.86km 11.1km)
X of second vehicle is (40000km / 360 degrees) * cos(10.0) * (10.2 - 10.0) = 21.86km
Y of second vehicle is (40000km / 360 degrees) * (10.1 - 10.0) = 11.1km
If you will try to apply flat line-line intersection for vehicles located in 10 000 km from each other - your calcutions most probably will be incorrect.
I am having a lot of trouble writing a code that will read in a latitude and longitude (NAD83) from a form, and convert them to VA State Plane North METRIC northing and easting. I am currently using Corpscon Beta 7 to convert a lat/long pair, but this requires that I go to an external resource to do so. I would like to preform the conversion in the database, so I can then query values from a table based on the northing and easting values.
I know that to transform the coordinates, I must use the following variables (I have already sourced their respective values):
Semi-major axis = 6378137.000
Semi-minor axis = 6356752.314
Central Meridian Scale Factor = 0.99994
First/Souther Parallel Lat. = 38.0333 deg
Second/Northern Parallel Lat. = 39.20 deg
Grid Origin Lat. = 37.6667 deg
Central Meridian Long. = 78.50 deg
False Easting = 3500000 m
False Northing = 2000000 m
I have done hours of researching and creating code, but nothing seems to produce accurate results, and most code that is found is converting Northing/Easting to Lat/Long, OR is done in a completely different language... and unfortunately I lack the knowledge to read and convert the code.
In my project I have to find [latitude, longitude] coordinate(s) from one point in distance of 500 meters (this could be any random coordinate or an array of coordinates around my point). How can I do this?
Note: I need this in order to find multiple paths between points different from shortest one which is returned us via Google Maps Directions Api..So using my method I will define the center of the road from A to B and then find some coordinates below and above that center position and use this as another waypoint to go from A to B - I guess this might help me to find multiple paths...
Any suggestions from GIS professionals?
EDIT: UTM conversion is the most preferable one for such calculations, and I've created UTM Java class if anyone needs..
If I understand your question right you have a known point in Lat/Long and you need calculate the Lat/Long of another point or points 500m away from your starting point.
If this is what you are doing, you have several options most of which involve specialist GIS APIs. However, I'm guesing you're a programmer/mathematician rather than a Geographer so, you may prefer to opt for using the Haversine formula. You can find a discussion on this topic here plus the formula.
One caveat is that the distamce you are working with (500m is quite small) and the Earth is far from being a perfect sphere or even a slightly flattened spheroid. It is locally "lumpy" and that can put your calculation out. If you need more accuracy you will have to account for these imperfections by using an appropriate local Datum (model of the Earth - there are many e.g. see EPSG list) and to do that you will probably need to start using the GIS libraries as the maths gets very detailed otherwise.
This is the code used by google map (SphericalUtil.java)
// from SphericalUtil.java
// compile 'com.google.maps.android:android-maps-utils:0.4.4'
public static LatLng computeOffset(LatLng from, double distance, double heading) {
distance /= 6371009.0D; //earth_radius = 6371009 # in meters
heading = Math.toRadians(heading);
double fromLat = Math.toRadians(from.latitude);
double fromLng = Math.toRadians(from.longitude);
double cosDistance = Math.cos(distance);
double sinDistance = Math.sin(distance);
double sinFromLat = Math.sin(fromLat);
double cosFromLat = Math.cos(fromLat);
double sinLat = cosDistance * sinFromLat + sinDistance * cosFromLat * Math.cos(heading);
double dLng = Math.atan2(sinDistance * cosFromLat * Math.sin(heading), cosDistance - sinFromLat * sinLat);
return new LatLng(Math.toDegrees(Math.asin(sinLat)), Math.toDegrees(fromLng + dLng));
}
to use it, you just have to enter the centerLatLng, the distance in meters, and the heading in degrees from centerLatLng.
you can change the formula to the language of your preference.
I have a database full of rows if coordinate pairs like this:
ux: 6643641
uy: 264274
uz: NULL
I have been tasked to make all these coordinates appear on google maps as points of interest, but nobody could tell me what the hell those coordinates were.
What I need for Google Maps is longitude and lengtitude coordinates. I know the one can be converted to the other, but nothing more.
I realize this might not be the correct place to ask about coordinate systems, but I honestly couldn't think of any other place to state the question.
Thanks for any help!
That's my bad, I now see that there is more data for each row:
CoordSystemNumber: 23
CoordSystemName: EUREF89 UTM Sone 33
I think that format is called UTM. You need to know the Zone and Hemisphere to complete the conversion. Is there other data associated with this?
Tell me if this seems helpful :
x = 882880 meters
y = -4924482 meters
z = 3944130 meters
Geocentric latitude and longitude are not commonly used, but they are defined by
latitude = arctan( z / sqrt( x^2 + y^2 ) )
longitude = arctan( y / x )
Taken from here :
http://www.cv.nrao.edu/~rfisher/Ephemerides/earth_rot.html
see this too :
http://en.wikipedia.org/wiki/Geographic_coordinate_system
This wikipedia article might offer some help.
The coordinates are often chosen such that one of the numbers represent vertical position, and two or three of the numbers represent horizontal position. A common choice of coordinates is latitude, longitude and elevation.
Dear everyone,
I'm trying to the find the hash function which can hash the key ( in string value) into XY coordinate.
For example: H("Doraemon") = (1.2345 , 3.2345)
If you have any information about this: algorithm , source code in C++ ... or something like that. Please share for me.
Thanks for your help.
Get the SHA-1 or MD5 hash, as bits, and take half of them for X, half for Y. Of each half, use as many bits (big-endian) as you can, for example use the first 64 bits of each half (out of 80) and there you have a double value.