New answers tagged lat-lon
Yes, they are related. One value or the other does not give you enough information for a location. You need to have both values to have a point in space.
One could use either kind of latitude to locate points on the WGS 84 ellipsoid (used by the NED) or any other ellipsoid, but "everybody knows" that the values will always be given as geodetic latitudes. However, it is surprisingly hard to find an authoritative statement to that effect! Before we go on, it helps to understand that although a datum like the ...
The answer is given in the metadata. Geographic coordinate system Horizontal datum of NAD83, except for AK which is NAD27 Both versions of NAD (North American Datum) are geodetic systems.
NAD 83 is the datum used to define the "geodetic" network in North America. NAVD 88 was established in 1991 by the minimum-constraint adjustment of "geodetic" leveling observations in Canada, the United States, and Mexico
Depending on the version/license of ArcGIS, you could use the 'XY to line' tool, in the 'data management\feature' toolbox. it produces a line feature from two sets of coordinates in a single table, which sounds like exactly what you are trying to do.
Here's one way it can be done: Change your data frame to a projected coordinate system that makes sense for your data. Calculate Geometry on 4 new fields X_incident, X_engine, Y_incident, Y_engine to populate the coordinates, using the CS of the data frame. Don't use the default, which is the coordinate system of the data! Calculate distance field with ...
If you project your data to a planar coordinate system in linear units (feet, meters) you could use the old pythagorean theorem. Note: This is not going to do the type of thing you'd get with network analyst (this will be euclidean distance aka "as the crow flies"). Lets say your fields are x1, y1, x2, y2. You'd create another set of fields and calculate ...
I have a similar ladder mnemonic. I picture a ladder |_| |_| |_| |_| | | So as you can see, longitude are the two "long" poles. Latitude is just "the other one", in this case the horizontal rungs or in your case the horizontal lines.
This is how I was taught in school: Try to say "laaaatitude".The corners of your lips go wide. Your mouth is a horizontal line, and so are lines of latitudes. Similarly, say "loooongitude". Your mouth is more vertical than horizontal. And lines of longitude are vertical.
I just think of the Corona Extra commercials where they say "change your whole latitude" and show a tropical beach scene. Unless you live in the tropics, that should help you remember :)
Sorry, I don't have an easy mnemonic to share. I just remember what I have learn in Geodetic Astronomy. Latitude is the "easy one" to measure, all you need is to measure the angle between the horizontal plan and the North Star (North Hemisphere ofc). Navigators would do it using an astrolabe. Longitude is far more complicated than that.
It is better to conceive of the earth on its axis, spinning in space around an orbit of the sun. In other words think about the earth in motion. Understand that there is a top and a bottom corresponding with North and South poles, or essentially where the axis around which the earth spins is located. Longitudinal lines emerge from these poles/locations of ...
(the most northern and southern climates are referred to this way) e.g. "Sky watchers in the northern latitudes will have a good chance of seeing Aurora Borealis." If the northern/southern latitudes are measured by the lat lines then they cannot use the vertical lines. They are horizontal and measure from equator north and south 0-90
From 3rd grade: lOngitude goes nOrth-sOuth
LATitude runs LATerally (sideways).
The trick of remembering latitude as 'ladder'tude always helped me. Think of a ladder standing up and the rungs of the ladder representing the E-W latitude lines.
A latitude-longitude pair is always expressed as e.g. "24 degrees 16 minutes north, 79 degrees 41 minutes west". ALWAYS North/South followed by East/West. So you just need to remember it's latitude-then-longitude, and thus latitude measures degrees north or south of the equator, and longitude measures degrees east or west of the prime meridian. That's how I ...
I always remember Longtitude as being "Long", where the lines do not change in length, and circle the globe. Also, Latitude being lateral, i.e. sideways
A lat lays flat. Can't think of a matching one for longitude.
Web Mercator has only real metres as units close to the equator. The more to the poles you come, the more x and y distances get apart. You should better use a "good" projection like the UTM zone of your area if you want to see the lines in correct length.
@MKennedy is right, the data are EPSG:21897, so you just need to declare that at load time, and then everything will magically work. shp2pgsql -s 21897 -W LATIN1 -D -I roads.shp roads | psql -d mycity And then see if you can get good geography coordinates out. SELECT ST_AsText(ST_Transform(geom,4326)) FROM roads LIMIT 1; Better! ? If you want to ...
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