I have a set of polygon points that have the SpatialReferences.WebMercator property. I need to convert these points to SpatialReferences.Wgs84 before saving to a database. Ideally I would just keep the WebMercator setting, but the existing database is using the Wgs84 format.
I am using the GeometryEngine class, but I noticed that once I reload the polygon, it is off by some way. It is in a different location. How can I make sure this conversion is accurate?
MapPoint point = new MapPoint(lon, lat, SpatialReferences.WebMercator);
MapPoint convertedPoint = (MapPoint)GeometryEngine.Project(point, SpatialReferences.Wgs84);
So as an example, I just drew a polygon with points -33.9360095288856 18,391141081041, -33,9075206517435 18,390454436898, -33,9303125156119 18,423413355855
After performing the conversion, the points became -36.1141869553583 18.0832273300021, -36.0798547481093 18.0825746003061, -36.1073205139085 18.113902885547
Related
I am trying to find an example, or documentation, on creating a picture (floating shape object) inside the Excel sheet. The source is supposed to be a numeric bitmap data, stored in a VBA array acquired using external I/O libraries. Using Excel cells as an intermediary storage is possible, but not desired, since the RGB bitmap data is expected to be huge.
The task itself seems to be extremely simple in matlab-like environments, or python. But I just have no Idea how to make it in Excel and VBA without importing an independent image file from the file system.
In terms of storing the file, how huge is 'huge'? If you convert the image into Base64, it'll be a fairly trivial task to split it up amongst the cells and then reconstitute it when converting it into an image.
Alternatively, you can store the Base64 string in a standard module - I'm currently doing much the same thing, but my image only clocks in at 100kb (better to save it as a PNG rather than BMP).
In terms of converting the Base64 string to an image, the Windows Image Acquisition COM object will convert a byte array into a stdPicture image type (and further to my point above, it will also accept PNG files...]. The following function accepts a Base64 string, converts it into a byte array, and returns an stdPicture object:
Function Base64toStdPicture(ByVal Base64Code As String) As StdPicture
Dim ImgVector As Object
Dim Node As Object
Set ImgVector = CreateObject("WIA.Vector")
Set Node = CreateObject("Msxml2.DOMDocument.3.0").createElement("base64")
Node.DataType = "bin.base64"
Node.Text = Base64Code
ImgVector.BinaryData = Node.nodeTypedValue
Set Base64toStdPicture = ImgVector.BinaryData.Picture
Set Node = Nothing
Set ImgVector = Nothing
End Function
From that point, you can out it in an image control, or copy it to / from the clipboard, etc.
I want to use long/lat (EPSG:4326) coordinates in a bokeh plot and have a map in the Background.
I tried with the tile provider maps as suggested in bokeh: Mapping geo data.
But the format is in web mercator coordinates (EPSG:3857) and I don't want to convert my coordinates.
The general question how to do this is unanswered in Is it possible to set figure axis_type in bokeh to geographical (long/lat)?
My idea was to use extra axes:
from bokeh.plotting import figure, show
from bokeh.models import Range1d, LinearAxis
from bokeh.tile_providers import CARTODBPOSITRON, get_provider
tile_provider = get_provider(CARTODBPOSITRON)
p = figure(x_range=(-180, 180), y_range=(-90, 90)) # EPSG:4326
# add extra axis
p.extra_x_ranges = {"EPSG:3857x": Range1d(start=-20026376.39, end=20026376.39)}
p.extra_y_ranges = {"EPSG:3857y": Range1d(start=-20048966.10, end=20048966.10)}
# place extra axis
p.add_layout(LinearAxis(x_range_name="EPSG:3857x"), 'above')
p.add_layout(LinearAxis(y_range_name="EPSG:3857y"), 'right')
p.add_tile(tile_provider, x_range_name="EPSG:3857x", y_range_name="EPSG:3857y")
show(p)
But the map is not visible.
Is there a way to use extra axis for a tile_provider?
If you are just asking about displaying lat/lng visually on the axes, then all you have to do is set the axis type to "mercator"
p = figure(x_range=(-2000000, 6000000), y_range=(-1000000, 7000000),
x_axis_type="mercator", y_axis_type="mercator")
This is demonstrated on the documentation page you linked.
If you are asking about using data that is in lan/lng coordinates to plot on a tile plot, then you will need to convert it to Web Mercator first. The underlying coordinate system for tiles is always Web Mercator.
If you are asking about something else, then your question is not clear (please update to clarify).
I am drawing one line from Location A to Location B using React.JS with Open Layers. I wish to get the Latitude and Longitude of the Location A and Location B.
I have added one listener after draw completion. But it is giving the co-ordinates as below . How can I get the latitude and longitude?
Listener:
draw.on('drawend',function(e){
console.log("Co Ordinates :",e.feature.getGeometry())
//console.log("Co Ordinates :",e.feature.getGeometry().getExtent())
});
Console :
Extent and flat coordinates values are printed in console as below
extent_:(4) [8732987.679175382, 1920132.5190330548, 8735555.9637923, 1920254.817578509]
flatCoordinates:(4) [8732987.679175382, 1920132.5190330548, 8735555.9637923, 1920254.817578509]
If you are just looking for a way to convert the coordinates you can use ol.proj.transform(coordinate, source, destination)
Using this
ol.proj.transform([8732987.679175382, 1920132.5190330548], 'EPSG:3857', 'EPSG:4326')
Will give this as output
[78.44976308230713, 16.99405070970775]
Also note that you can use getFirstCoordinate and getLastCoordinate methods on the line feature to get the first and last coordinates.
OpenLayer is working on different location formats like EPSG: 3857, EPSG: 4285 etc.
There are some Transform/Projection api enter link description here
Use this api's and transfer your locations to your desired formats
I get following exception when using Entity Framework to get data from bounds from a google map:
FormatException: 24201: Latitude values must be between -90 and 90 degrees.
POLYGON((81.9882716924738 140.187434563007,21.5587046599696 140.187434563007,21.5587046599696 -40.1641279369925,81.9882716924738 -40.1641279369925,81.9882716924738 140.187434563007))
I can see other have same problem, but havent found anything that solves this. I would expect that first coordinate for point is the latitude and second for longitude? And none is above 90 so why do I get this error? I tried swapping lat and lng but with same problem.
This is the failing line:
var poly = FindByBoundingBox(northEastLat, northEastLng, southWestLat, southWestLng);
DbGeography polygon = DbGeography.FromText(poly, 4326);
var parksWithinPolygon = dbCtx.SiteList.Where(p =>
p.PolygonCenter.Intersects(polygon)).Select(p=>p.SiteName).ToList();
As Damien states first problem is that Sql server expects longitude first and then lattitude. This throws another error, redirecting to another problem:
"This operation cannot be completed because the instance is not valid".
My best bet is it's the they way/order I build the polygon. Has anyone succeeded in mapping google bounds to a polygon in SQL server? In short I am trying to get any data (data has a point column) within the google map bounds.
The function to calculate polygon is listed below:
public string FindByBoundingBox(double northEastLat, double northEastLng, double southWestLat, double southWestLng)
{ //Create poylgon of bounding box
System.Globalization.CultureInfo customCulture = (System.Globalization.CultureInfo)System.Threading.Thread.CurrentThread.CurrentCulture.Clone();
customCulture.NumberFormat.NumberDecimalSeparator = ".";
System.Threading.Thread.CurrentThread.CurrentCulture = customCulture;
var bboxWKT = string.Format("POLYGON(({1} {0},{1} {2},{3} {2},{3} {0},{1} {0}))", northEastLat, northEastLng, southWestLat, southWestLng);
return bboxWKT;
}
OK i figured it out. As Damien stated the order of coordinates is oppesite of google. In SQL long needs to be first. Next thing is what is the "left hand rule". You need to create your polygon starting from lower left corner and then counter clock wise.
I have spent dozens of hour trying to find is it possible to change projection with mapserver with no luck so far. My input format is EPSG 3067 and I need to convert it to EPSG 900913 for Google Map use.
In the MAP object add
PROJECTION "init=epsg:900913" END
this sets the output projection of the map. Then in t LAYER object add
PROJECTION "init=epsg:3067" END
this set the projection that the incoming data for the layer is already in.
You will also need to add the following line to your /usr/share/proj/epsg or the equivalent path if you are on Windows:
Spherical Mercator projection
<900913> +proj=merc +a=6378137 +b=6378137 +lat_ts=0.0 +lon_0=0.0 +x_0=0.0 +y_0=0 +k=1.0 +units=m +over +nadgrids=#null +no_defs <>