Questions tagged [geography]

Questions using this tag are likely to be off-topic because this is the Geographic Information Systems (GIS) Stack Exchange and its scope does not stretch to general geography

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24 views

What CRS is my data being transformed to in ST_Project? What about ::geometry?

My understanding is that ::geography transforms data from whatever CRS into 4326. But what is ::geometry doing? Relatedly, in the context of the ST_Project function: st_project(a.geom::geography,b....
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26 views

Different results for GEOGRAPHY and ST_TRANSFORM query on geo_point field

I am finding properties that are within 20K distance using ST_DWithin. But when I try with ::GEOGRAPHY casting the result is different from ST_Transform. Note: SRID of geo_point field is 4326 Indexed ...
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44 views

QGIS Convert Shapefile to MSSQL as geography type

I am using QGIS 3.16 and SQL Server 2019. I have a shapefile loaded into the project. I have been able to successfully convert the Shapefile to a spatial dataset in SQL Server. My method for doing ...
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1answer
31 views

Dissolve shapefile polygons on SQL Management Studio 18

This is the first time I am trying to work with a shapefile on SQL and I am a little lost. I uploaded a shapefile with all the counties of the US and what I am trying to do is to dissolve all ...
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1answer
329 views

ST_GEOGFROMTEXT Multipolygons converted to Polygons BigQuery

My table contains multipolygons in column called BoundaryWKT, which is in a string format. I used function ST_GEOGFROMTEXT(BoundaryWKT) to convert column of multipolygons from string format to a ...
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1answer
81 views

GPS coordinates coming from vehicle connect to streets coordinates

I have two tables: "Vehicle" includes GPS coordinates from the moving vehicles and has around 3.000.000 rows "streetCoordinates" includes GPS coordinates of the streets, where the ...
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1answer
73 views

Spatial and DateTime join in SQL BigQuery

I have 2 tables in BQ; one of them includes a geography column PointWKT (gps POINT) and second table includes a geography column BoundaryWKT (POLYGONS & MULTIPOLYGONS). Both tables also include ...
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1answer
284 views

Increasing Contrast of Topographic Image in R

Brand new to R, so a little foreign to me, but I Created a topographic image using Landsat, and .hgt data. I got an image out but tried to increase contrast using the scales tool. It is still giving ...
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698 views

Rendering 3D map in pgAdmin 4 to view Data? [closed]

I found this error 3D geometrics not rendered in view data (pgAdmin 4). In GeoDjango I've updated my PointField model with dim=3. After successful migration, I cannot see my data in map. My Django ...
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2answers
116 views

Straight line through the earth (not core) from America to which country? [closed]

If you were to draw a straight line, or dig a tunnel, through America, where would you end up? To clarify: Let's say you have a globe that sits upright on a table so that the south pole is on the ...
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75 views

Dealing with non-nested geographic units using the RQGIS and tigris R packages

I recently came across this tutorial suggesting that the RQGIS and tigris R packages could be used to overcome issues with non-nested geographies: https://rpubs.com/corey_sparks/256942 I'm trying to ...
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1answer
242 views

Area between two longitudes? [closed]

I am trying to compute the area between two longitudes (using the angle between them) but am having a hard time. I can do that more easily between latitudes but longitude reveals to be tricky. Anyone ...
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714 views

Use Natural Earth data set in Cesium

I have saved NaturalEarth data set in my desktop. Then I created a view as below. <script> var viewer = new Cesium.Viewer('cesiumContainer', { ...
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2answers
3k views

Using SqlGeometry.MakeValid to get a counter-clockwise polygon in SQL Server

The data I've loaded from a shapefile into a geometry column in SQL Server (using NetTopologySuite) is not producing valid GeoJSON when I export it because it doesn't follow the right-hand rule. I ...
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2k views

When does WKT orientation matter for polygon and multipolygon in geography spatial (left/right hand rule, counter-clockwise, clockwise)

I've decide to use sql server on Azure for my gis database. I'll be dealing with spatial Geography not Geometry. While inserting some country boundaries using the spatial data in SQL Server, some ...
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1answer
85 views

Kriging: Large standard error very close to known value points

I am attempting to create surfaces of strata via Kriging in Arc GIS from borehole data. In addition to the predicted surface I also want surfaces showing 95% confidence above and below the predicted ...
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1answer
217 views

Number of Eastern Africa countries [closed]

Are Rwanda and Burundi part of "Eastern Africa countries" or "East African countries". Some sources are differing.
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1answer
88 views

Alternative ST_NumGeometries in type geography

In PostGIS (2.1.8) I use function ST_NumGeometries for nums of count geometry. This function have one argument 'geometry' type. I need this function for geography type. I looked for but I didn't find ...
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1answer
96 views

Malaria Mortality Rate GIS Data [closed]

Can anyone direct me to GIS data for malaria mortality rate? I am looking for countries in South Asia, but not looking for country level numbers but smaller level numbers like district level.
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1answer
338 views

In PostGIS how can I do an ST_Intersection() search with a GEOMETRYCOLLECTION Geography field?

I have a Postgres table "files" with a lat/lon location field of type geography(GeometryCollection,4326). Right now the field only contains lat/lon polygons. I have succeeded in creating a gist index ...
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1answer
2k views

Calculate vertices' coordinates of a rectangle, given midline and broadth of rectangle

I have latitude and longitude of two points making the midline of a rectangle. Now I want to determine coordinates of 4 vertices of that rectangle. I know how to calculate on plane geometry by using ...
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3answers
6k views

Which is the most accurate method of measuring distance?

I aim to analyse the accuracy of the various methods of geodesic calculations (distance between two points on Earth)based on the three assumed models of Earth - flat, spherical & ellipsoidal. I ...
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1answer
2k views

Distance from point stored in geometry with SRID 4326

I have stored 2.5 million data points (addresses) using the geometry data type in column latlong with SRID 4326. The latlon - column has a GIST index defined. I would select all addresses within a ...
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1answer
61 views

Half of Earth with most landmass [closed]

About 71% of the Earth's surface is covered with water and the remaining 29% is landmass*. If you could theoretically cut the planet in half, with the objective of producing a half with the most ...
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0answers
52 views

CartoDB geom (coordinates) join: without exact match

Trying to join two datasets (layers) on CartoDB based on their geographical fields (in CartoDB's the_geom created field). However, the basic ST_Intersection function does not work since its tolerance ...
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1answer
408 views

PostGIS - st_intersects using polygons that cross antimeridan/equator

New to using PostGIS and have two situations that I'm working with. In the one case, I have a polygon that crossed the antemeridian and was detecting whether a two separate points located within that ...
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1answer
250 views

Use QuadTree for better complexity on search features

I want to improve the complexity of search specific feature when using this function : map.forEachFeatureAtPixel(e.pixel, function (feature, layer) { // Do something.. }); The improvment ...
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1answer
128 views

“polygon” on sphere postgis geography

I have a set of points defined by their longitude and latitude, and I would like to check if they lie within a "polygon" on sphere. By polygon on sphere, I mean area in between 4 lines going between 4 ...
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2answers
1k views

GeoJson to Spatial Geography in sql server 2012, fix orientation of polygon

I've download from Mapzen many geoJson files related to countries with their respective administration level. Then I've parsed all the geoJson files and saved them to my sql server 2012 as geography ...
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1answer
45 views

Territories that are not connected

I am looking for territories that are divided between two or more countries in a non-contiguous way. E.g, country A receives the western part of the territory, then country B receives a part to its ...
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0answers
75 views

Quantifying amount of sunlight falling in a region

I am trying to objectively quantify or provide some form of indication that could point toward the amount of sunlight Anyone knows if there are any datasets (either instrumental or remotely sensed ...
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2answers
493 views

Is there any online viewer which displays the polygons assuming great circle lines for the edges?

My question is similar to this one: Are there any online WKT editors? The links given in answers have been very useful to me. However, it seems that when the tools in question display maps, they ...
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1answer
73 views

Location based service with normal image

We have an image for a park which has been rendered like this: Now we want to add some geographic service based on the data: building an Android Application with the following features: Display the ...
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1answer
158 views

ArcPad custom edit form validation behaviour

I have a custom ArcPad form, which includes the geography tab. Users use this tab to update coordinates using the GPS. When user press OK in the edit form, I want to first check that they have not ...
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2answers
5k views

Order sql server spatial geometry distance by the nearest

I have a geometry column in a table, I want to get the N nearest neighbours; here is a specific example with the geography type DECLARE @PTO Geography = Geography::STPointFromText('POINT(-57.432546 -...
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0answers
187 views

Needing to find parent zip code of a bunch of missing zip codes in the US [closed]

We're using MapPoint to export zip code / territory combinations. Unfortunately, the export doesn't include PO Box zip codes which mean that we're missing a lot of zip codes The PO Box zip codes are ...
3
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1answer
157 views

GIS through Games: Ideas or Links [closed]

I'm managing a project - http://nepanode.anl.gov aimed at improving data awareness and sharing around Environmental impact analysis. I'm struggling to come up with ways to engage users and show them ...
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2answers
20k views

Equations to convert from global cartesian coordinates to geographic coordinates

First, I needed to convert geographic coordinates (like those received from GPS) to global cartesian coordinates. I found an earlier question (How do I calculate a xyz-position of a gps-position ...
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2answers
12k views

Geometry datatype to latitude /Longitude MS SQL Server

I need to convert Sql Server geometry datatype to latitude /Longitude I have just imported a shapefile to my table (geometry) This query does not work:- select geom.Lat as [Latitude], geom....
2
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0answers
47 views

Characterizing territory according to its relief using ArcGIS Desktop?

I want to characterize the territory according to its relief with ArcGis 10. I'm trying to define a wide territory by its relief, but I would like to do it in an automatic or semiautomatic form with ...
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1answer
1k views

The ratio Pixel distance to geographical distance?

I have had this problem for several days and I have no idea to solve it. The problem is that I am trying to find out the length and width of ships from a Bing map. I got the location point (lon, lat)...
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1answer
484 views

What is the radius of earth [duplicate]

What is the real radius of earth? Google says 6378.1 km Wiki says 6371 km And there are references for 6378.7 km I'm using maximum radius 6378.7 km in distance calculation in spherical law of ...
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1answer
70 views

Postgis add Geography to function()?

i was wondering im getting different results when using geography() on different positions within a query. So, whats the most accurate way of forcing geography() over a functions with geometry ...
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1answer
229 views

Learning classical geography - recommended literature etc

I've been working in the field of GIS for a few years now, and there are some disciplines of knowledge where I lack a good degree of education. My educational background is that I've studied computer ...
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7answers
5k views

What is the easternmost point in the US?

In his blog for The Atlantic magazine, James Fallows claimed that Eastport, ME was the easternmost point in the US. A writer commented that no, the easternmost point in the US was somewhere in Alaska, ...
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2answers
2k views

Min. weighted average distance from multiple points

I am a complete beginner in mapping-related topics. Still, I´ve been wondering if anyone know this problem. It might be well known, I just don´t know its name. Initial situation: nx : x geographical ...
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1answer
75 views

Countries with a small number of sides

Please accept my appologies if this question is off-topic here; this is the closest match to the topic of my question. I am looking for countries and states whose map is a polygon with a small number ...
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1answer
1k views

Convert an area to meters² in PostGIS

I have this query : SELECT ST_AREA(geom::geography) FROM region The (geom) contains polygons from a shapefile imported into PostGIS with shp2pgsql. I've appended ::geography, else the result of the ...
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3answers
969 views

Where can I publish my paper for free?

Is there any magazine (or some other such place) where university students can publish a GIS/Geo related article freely (in English or French)?
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2answers
4k views

Shapefiles for US city and Zip level

I already have the information for US states and Counties. I have the information in the JSON files. I want the information for ALL US city and Zip Code information. I can't really navigate the US ...