0
votes
1answer
16 views

Trouble Using Selection Expression in QGIS

I am trying to use the selection expression box to highlight counties by state FIPS. When I use the OR conditional all counties across the US get highlighted. So for example, STATEFIPS = 1 will ...
1
vote
1answer
60 views

Delete duplicate spatial point/points in mssql from a perticular location

I am working with a Spatial data which has a street intersection points.... I get the intersection points from spatial query on street/roads datain MMSQL . but in my case some streets/roads are multi ...
2
votes
0answers
43 views

how to assign unique attribute value per neighborhood? [duplicate]

I have a feature class of adjacent polygons and I want to assign an integer attribute value to my polygons based on the following rules : a polygon must not have the same attribute value than any of ...
0
votes
1answer
147 views

How can I always run an algorithm with standard input shapefiles from mapcanvas in QGIS 2.0.1?

I created a model in the graphical modeler and I want to run that model always with two specific polygon shapefiles from my project, e.g. pst and astenot. Whenever I run my model, it asks me to set ...
3
votes
5answers
350 views

How can I count overlapping polygons, resulting in a new set of polygons?

I have 100 polygons in a GeoJSON file that partially overlap each other. I would like to produce 100 new polygons as follows: The area covered by any of the original 100. This is their union. The ...
6
votes
1answer
112 views

Open source implementation of “feature density” algorithm

I'm working on a dataset of house searches - 1 polygon for each area in which people want to find a house from an online search tool. This produces many overlapping polygons. It would be great to ...
1
vote
1answer
191 views

How does QGIS calculate the area of a polygon?

I am working on a project that requires the calculation of the area of a polygon by two different methods. I need to know what algorithm QGIS uses to calculate the area of a polygon. I know ESRI ...
2
votes
0answers
114 views

oil palm stand census algorithm

Anyone have experience in oil palm stand census using tree detection algorithm from satellite images in ArcGIS or QGIS? any references for usable algorithm? What is the accuracy? thanks for help.
3
votes
2answers
2k views

How to split a line at point positions?

I am a rooky with QGIS and i am stuck from a basic problems. I have a polyline and i have some points (2) on the polyline. I would like to know if there is a tool or script that i could use to ...
5
votes
2answers
246 views

Raster calculation confusion

I need to do some raster calculation, I've been trying to make it work but I am not sure everything is working properly. I need to apply a formula, but I am unsure if I am doing it properly. The ...
4
votes
1answer
934 views

How to create a polygon from other polygon boundaries?

I want to write an algorithm that creates a polygon inside a hole made by a set of other polygons. It's something like a flood fill and it's like the "boundary" tool in Autocad. The image shows an ...