(1) abstract geometry; (2) storing geographic data in projected coordinates; (3) a generic ESRI term for vector features; a class for "geometry" objects.

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9
votes
1answer
649 views

How exactly is the centroid of polygons calculated?

I would like to know how exactly QGIS Geometry tools -> polygon centroid is calculating the point coordinates. For example does it divide the boarder of the polygon into small points, take two pairs ...
1
vote
0answers
42 views

Is there a way to select polygons by geometry (right angle)? [closed]

Is there a way to select polygons by geometry? I need to find a way to detect all the polygons that have a right angle, but I can't find a tool that can do that. I'm using QGIS 2.10.1 and ArcGIS ...
3
votes
1answer
603 views

Update a table with values from coordinates on GEOMETRY in Oracle

I have 2 columns in a table that represent the X and Y coordinates. The values in those columns don't match the actual coordinates and I want to update them with the coordinates values that are ...
0
votes
1answer
47 views

How to get Lat/Lng from a Geometric property?

Alright, I am very new to GIS, my question might not even make sense, but help me get through this. I have this JSON data of some fields which have this geometry property: "geometry": {"type":"...
1
vote
0answers
17 views

Quantum gis 2.2 - pasting templates

Is there a way to paste geometries in a workspace at the location i want? e.g. i want to paste a circle from another workspace in the workspace i'm working with. I need only the geometry, not the ...
1
vote
2answers
188 views

Can QGIS import Multipatch geometry type?

can QGIS import multipatch 3d geometry type? What is the data structure of multipatch how computer record and draws it ? Is it solid or not??
0
votes
1answer
260 views

PyQGIS: how to transform single QgsGeometry object from one CRS to the other?

I have a polyline layer with roads in WGS84 that covers several UTM zones. For every road I need to place a set of points at different distances (in metres). To do so I want to reproject each road to ...
1
vote
1answer
96 views

What does double digitized polygon mean?

I know what is a polygon but when a polygon is said to be double digitized? I failed to find a suitable meaning of double digitized after googling. I understand double digitized means digitized twice,...
0
votes
2answers
389 views

What is nontopological geometry?

I need a simple understanding of nontopological geometry. I am completely new in this area so please correct me if I am wrong. As far as I understand in topological geometry the object(say a line) ...
1
vote
1answer
352 views

Querying Oracle geometry data type

How to query or find the geometry data type a given Oracle Database is using in SQL Developer (i.e. SDO_Geometry, ST_Geometry, etc)? I thought I could just describe a feature class within the ...
2
votes
0answers
69 views

Geometry issues when digitising in QGIS

I'm digitising a large number of maps from hand drawn mud maps and digital images, and although I have used the snapping tools ("snap to vertex and segment", Tolerance 10 pixels, avoid intersections) ...
1
vote
0answers
143 views

ArcGIS/ ArcPy - XY coordinates of feature class does not match calculated geometry XY

Tested on: different workstations, different Windows versions; ArcGIS Desktop 10.3, different license levels Background: I use the Google Maps DistanceMatrix to calculate drive times between two ...
2
votes
1answer
102 views

Create geometry from a result of intersection [closed]

Split a polygon in half with an extended line public Ipolygon CreatePolyFromIntersection(Ipolgon polygonA, Ipolygon bounradyThatcontainsPolylgonA, IFeature lmark){ ...
2
votes
2answers
106 views

Query Features in Certain Direction

I have a polyline that I would like to query features that are on it's left, right, top, bottom. I am not looking for the features surrounding it but for features that are on a certain location from ...
0
votes
1answer
134 views

Qgis 2.10 unable to add a new feature in spatialite via sql function “GeomFromText”

Using Python code in my plugin the function in sql language "GeomFromText(POINT(X Y))" gives the following error: "OperationalError: no such function: GeomFromText" Plugin functions in previous ...
8
votes
3answers
2k views

How to convert from SQL Server geometry BLOB to something else?

I have a CSV data file from a 3rd party that is an exported SQL Server table. They simply did a select * from foo and output the result to a text file and sent it over. In their table is column of ...
0
votes
0answers
28 views

Determining North-South Line Via Watch Method?

I read about Determining North-South Line Via Watch Method recently (page 9). What is the underlying geometric/celestial reason this works? What is the error to true north given this method? Is ...
1
vote
1answer
93 views

Shared edge between two geojson polygons

I am interested in getting the coordinates of a shared edge (if exists) between two geojson polygons. I am (currently) using turfjs and geojson-equality libraries I tried this but I consider it quite ...
2
votes
1answer
273 views

Remove inner rings from QgsGeometry polygon in QGIS Python

I am a QGIS python user. I want to iterate over the rings of a polygon to remove holes in the polygon, so: I need to iterate over the rings in a QgsGeometry polygon I need to detect the main ring ...
5
votes
2answers
154 views

Polygon points to Polyline

I am trying to create a polyline from the points that I query from a polygon. I have a polygon, and I am getting its edges, casting them to segments, and then use QueryNormal to get the mid point ...
1
vote
1answer
1k views

How to resolve the postgis “type geometry does not exist” issue on installing tiger_geocode extension?

I have installed postgis extension in my db. I have few columns associated with its type in few tables and now I would like to use reverse geocode functionality in my app. Hence I tried to create ...
2
votes
0answers
55 views

how to register view geometry made by MakeLine function?

I am trying to to create a spatial view on my spatialite database. CREATE VIEW v2_pump_view AS SELECT pump.ROWID AS ROWID, pump.id AS pump_id, MakeLine( ...
6
votes
2answers
426 views

Draw SQL server geometry records as graphics on map using ArcGIS API for WPF 2.4 -can it be done and how?

I have records (of public festivals changing daily) in the in SQL server 2012 that have a geometry column (polygons where they occur). I need to show the records as graphics on a map using ArcGIS ...
1
vote
2answers
36 views

Geographical Field Points of a Boundary

I gathered field points with a TOPCON hand held receiver. I saved the points as a shape file and brought them into arc map. I used the editor tool to connect the points and created a polygon. Is ...
3
votes
2answers
107 views

Construct curve of equal distance from two straight lines

Given two straight lines defined by two points each, I want to get the line which separates points nearer to line a from points nearer to line b. The attached PostGIS code is an example case, it finds ...
0
votes
0answers
34 views

PosGIS: Longest line connecting point to line

I have a point and around it lines and polygons in the rule of obstacles. I want to connect the point to each of the lines, with a line, such that this connecting line is not intersect any obstacle (...
1
vote
0answers
46 views

sql server geometry find points intersection buffer

How do I find the point of intersection of buffer?
1
vote
1answer
102 views

GeoTools Geometries lost when storing features to shapefile [duplicate]

As you know, the geometry column name of schema for saving into a shapefile must be "the_geom". I have a SimpleFeatureCollection with a schema, geometry name of which is not "the_geom"; It is "...
3
votes
2answers
134 views

Testing if Geometry is convex using JTS?

I'm using the Java Topology Suite and I'd like to efficiently check if a Geometry (a Polygon in fact) is convex or not. I currently do if (geometry.convexHull().equals(geometry)) but obivously that ...
0
votes
0answers
14 views

Representation of streets/highways Geometry

I have Navtech data which provides center-lines with geometric data of the roads. The most important data for me is that it gives me the width of the road as well as the number of lanes for most of ...
0
votes
0answers
222 views

Drawing Zoning Setback Lines

What would be the process for drawing zoning setback lines for a property parcel polygon? I'm looking for a software agnostic solution - just a walk through of the general steps with enough detail ...
1
vote
1answer
54 views

Looking for geometries defining the boundaries of Canadian Location Code regions used for Meteorological Services in Canada

To be clear I have looked into the GADM datasets. The problem is that Canada has a very non-standardized level-2 Administrative Zone identification across the various Territories and Provinces. As a ...
0
votes
0answers
89 views

Remote SQL Server, Crystal Reports and Geospatial Join

I have: A remote SQL server (2008 R2) that I have access to (But NOT full control of) which contains my source data including OSGB 1936 Geometry [ESPG: 27700] In house SQL Server 2008 R2 A Crystal ...
0
votes
1answer
39 views

Double geometry coloumns in an xy event layer (ArcGIS 10.0)

I want to convert an annotation feature class to a shapefile. The annotation feature class is stored in a file geodatabase. I add two columns (x, y) for the centroid coordinates (calculate geometry) ...
1
vote
1answer
59 views

sorting polygons extracted using Fishnet

I generated polygons using fishnet in ArcMap, since the polygons didn't fall exactly on top of my raster image, I had to edit and move some of them. Now the FID of my polygons are all messed up, and ...
0
votes
0answers
157 views

How to create a polyline using multiple points using a PostgreSQL query?

I'm trying to use point data to create a polyline to show my bus route. Initially began with coordinates and used this to create geom using the ST_MakePoint function (written to the BusRouteData table)...
1
vote
0answers
21 views

QGIS 2.0.1 Translate Feature

I have a layer containing linestrings and want to move those that are too close to each other. I seem to be missing something in the moving part though: layer = iface.activeLayer() def moveFeature (...
2
votes
2answers
169 views

Merging lines (that might cross) at common endpoints without multi-part features in the result

I have a polyline dataset I'm trying to merge / dissolve segments based on an attribute into continuous single lines. The problem is that some of those segments cross each other but need to be ...
9
votes
2answers
96 views

Fuzzy least-coarse common partition algorithm

Given two different partitions of a shape (for argument's sake, two different administrative divisions of a country), how can I find a new partition into which both of those partitions fit, allowing ...
0
votes
2answers
104 views

Using ST_LINE_INTERPOLATE_POINT in OGR and python

I'm interested in finding the midpoint on a linestring using OGR and python. This can be a line with more segments. Could I use the ST_LINE_INTERPOLATE_POINT in python using the ExecuteSQL() method? ...
2
votes
0answers
125 views

how to orthogonalize building outlines

I'm looking for a way to orthogonalize building outlines which I've extracted from a high-res DEM. I'm using the FOSS GIS stack (QGIS, GRASS, SAGA, PostgrSQL, PostGIS) and can code in Python (or Java)....
1
vote
0answers
43 views

Geometry Calculation in QGIS [duplicate]

I'm trying to calculate the area of some census tracts in qgis I go to vector -> geometry tools -> export/add geometry columns in the resulting dialog, I calculate using project CRS. What comes out ...
1
vote
0answers
28 views

WFS Updating a geometries points

I'm trying to work out on how I can insert or overwrite points that are stored in a features/ Layer? I've created a String/Text document which is already converted into GML/XML ready to be pushed to a ...
1
vote
0answers
27 views

line from min to max of a digital elevation model

I have some geometries as multipolygons and a dem (digital elevation model). I need a line from the max value to the lowest value of the dem for every multipolygon. Is qgis a tool i could use or do i ...
1
vote
2answers
123 views

How to get ST_MakeLine ready for QGIS?

CREATE VIEW new_line AS SELECT point1.gid, ST_MakeLine(point1.geom, point2.geom) FROM point1, point2 WHERE point1.gid = point2.gid; It's possible to load the layer but QGIS says 'There is no entry ...
5
votes
2answers
316 views

Cutting a circular buffer via Arcpy

I am currently working with compressor stations on centerline routes. These compressor stations have a 3 mile buffer surrounding them. I wish to cut a portion of the circular buffer off. These cut ...
0
votes
1answer
182 views

MS SQL table with geometry field to feature class

I have a table in a native SQL database (no geodatabase, dc_geobank_public.sde in the code) with cca. 300 000 records and 18 fields. Two of the field contains projected X and Y coordinates, and one ...
3
votes
0answers
694 views

C# implementation of concave hull / alpha shapes

I'm looking for a C# implementation of the Concave hull (alpha shapes) algorithm. I already found several Java, Python and C++ implementation but no C# version. The other implementation are quite ...
0
votes
0answers
195 views

Explanation of the Thinness ratio formula?

I am looking for sliver polygons and am using the following formula to identify which polygons have a smaller area-to-circumference ratio (aka Thinness Ratio): 4 * pi * area/(length*length) That ...
1
vote
0answers
26 views

Forcing area calculation into miles in QGIS (without changing the PCS) [duplicate]

I'm working on an assignment that requires me to create an area column in miles without changing the projected coordinate system. ArcGIS has a tool that can do this ('Calculate Geometry')-- does QGIS ...