I want to draw a polygon ( or even better to use already defined lat.long) in Tableau map.
is it possible?
Regards
Yes, choose the polygon mark type, put latitude and longitude on the row and column shelves and a field on the path shelf to specify point order.
Use other dimensions on additional shelves such as detail or color if you have multiple polygons to display
Related
Is it possible to use HERE vector maps in openlayer? The example on the openlayer site uses raster maps but not vector.
As stated in the comment section by Younjae Park:
HERE Vector Maps follows the Vector Tile Specification. This format contains geometries, such as points and lines that define polygons, labels (such as road names or city names), and other kinds of data that are typically passed to a renderer to draw a map. The tiles are optimized to be visualized as 512px screen pixels per tile.
Please have a look also a look at Vector Tile Specification of Openlayer.
I have two tables named polygon & paths which contains polygons data and paths(line string) respectively. I am trying to build a query in which I will pass lineString data and on the basis of that, I want to fetch all the polygons which that lineString intersects.
I am quite new to this Please suggest some approach by the help of that I can be able to achieve this.
Thank you.
You question is very general. But if you want to get the polygons that intersects with the line then the query in postgis would be something like this
SELECT p.* FROM polygon_table AS p, line_table as l
WHERE
st_intersects(p.geom, l.geom)
geom are the columns representing the geometry column, and make sure that both tables have same SRID.
I am trying to do a grid based clustering, specifically where each U.S. state is a grid. What I am doing now is just setting strategy option of ClusterProvider to STRATEGY_GRID_BASED, but I don't think this is what I think it is.
I tried looking into nokia.maps.clustering.IGridOptions, but there isn't anything documentation on that.
Can someone point me in the right direction? Thanks.
A Grid-based clustering strategy just breaks the map up into squares and calculates how many markers are found in each square. What you are after is known as a Chloropleth Map. The most efficient way to do this would be to cluster server-side, return a key,value pair (i.e. state, number of markers) and just display polygons for the US States. An example of such a map can be found in the HERE Maps community examples which displays the accession dates of states to the union.
If you insist on doing everything client side then you'd have to use the following pseudo code instead:
Iterate though each marker in your list:
Check to see if it is within the hit area of an existing polygon.
If it is - increment the markers counter (an additional attribute you have added.)
If it isn't make a WKT State-level shape geocoding request, and parse the result -add a new markers counter attribute to the Polygon
repeat
You will then end up with a series of polygon objects each holding an attribute with the number of markers within found within the state.
I am creating a mapping application which users can interactively draw a polygon on a Google Map.
I need to send this polygon data back to a Sql Server and determine which records to return based on their LatLng positions in the database being within the polygon.
Does anyone know how to do this or a routine that is available.
Thanks in advance
If you have a geography column associated with your records, you can use that to query for items within a polygon. Link to get you started. Here's an example:
--What Items are within the Bermuda Triangle?
---Note that Well-Known Text representation of a polygon is composed of points defined by Longitude then Latitude.
---Note that the points are defined in a counter-clockwise order so that the polygon is the interior of the triangle.
DECLARE #BermudaTriangle geography = geography::STPolyFromText
('POLYGON((
-80.190262 25.774252,
-66.118292 18.466465,
-64.75737 32.321384,
-80.190262 25.774252
))', 4326)
SELECT ItemID, ReportedGPSPoint.Lat, ReportedGPSPoint.Long
FROM Items
WHERE ReportedGPSPoint.STIntersects(#BermudaTriangle) = 1
A question from a novice. Is it possible to design a tool to select color range and create a vector map within that given range to integrate into a flash tool? basically a feature that mimics the wand tool effect in photoshop, but creating a vector outline of the range selected. Any reading material to help with this would be greatly appreciated.
I think you are looking for either 2D segmentation, if you want all the selected colors in the image to be selected, or flood fill if you want to find the region surrounding some initial point where all the colors are in the desired range.
When you say vector map, I imagine you mean the outline of the pixels to select. In which case it's probably easier to find the pixels you want and then draw round then rather than explicitly creating a polygon to contain them.