The abstract study of topics encompassing quantity, structure, space, change, and other properties

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3
votes
1answer
38 views

Convert Raster into Cell by Cell Table

I'm hoping to run some Python mathematics on a raster, outside of ArcGIS. It's important to have a cell by cell table for the analysis I want to run. I plan to store it in a python dictionary similar ...
1
vote
2answers
43 views

How to take cosine squared of raster using python

I have an equation y = cos^2(x) where x is a raster. How can I write this equation in python?
2
votes
1answer
49 views

Comparing two maps with two different libraries

I'm currently making a demonstration to compare the two OpenLayers libraries (2 and 3). For doing this, I have made two div elements and put the different maps on each other. The goal is to make a map ...
2
votes
2answers
40 views

Formula for charting a course around the globe, given a location and degree heading?

I'm looking for a formula that takes a long/lat coordinate and a degree heading, (e.g. "I'm standing in San Francisco and I'm facing 45º from north"), and which can draw a line across a map projecting ...
1
vote
1answer
47 views

Finding the shortest distance between a point and a line

I read and understood the following GIS question and the accepted answer, calculating-the-distance-between-a-point-and-a-virtual-line-of-two-lat-lngs I can return the value in the ShortestLength ...
2
votes
0answers
36 views

Is there a method to tell which hemisphere a point belongs to, in WGS84 geoid, where the equator is an arbitrary ellipsis?

I use the WGS84 geoid (because I'm working with a GPS chip). I define an ellipsis that splits the surface in two parts, lets name these 'A' and 'B'. This ellipsis is defined by two points 'a' and ...
2
votes
1answer
53 views

How can i add script with math functions to model builder?

I am very new to model builder + python. (Sorry for my english too) I am trying to make a model. Don't know if it matters to upload it. If you want i can. I want to calculate variance from a ...
0
votes
0answers
35 views

Calculate end point Height above the MSL of the target point given a starting point, distance, azimuth and elevation [duplicate]

We need to find the end point height (from the earth surface) given the start point lat, lon, azimuth (270 deg), distance (500 km) and elevation above the horizon of start point (10 deg). The ...
0
votes
0answers
64 views

Offset WGS84 linestring based on pixel values

I would like to split up some roads based on their driving direction. For this, I need to offset the roads 2 pixels to the right, in the direction of the linestring. I have the coordinates in WGS84 ...
0
votes
0answers
25 views

Find square with latitude and longitude for given lat and lng and distance [duplicate]

I have the coordinates of some point, lets say lat and lng, I want to find the latitude and longitude of top left and bottom right corners of the square, whose sides are located k kilometers from the ...
0
votes
1answer
147 views

Do I need to run regression in each samples separately?

I'd like to do smooth NDVI image by regression analysis; response of time series NDVI image to Julian date to represent the seasonal changes in NDVI as a function of Julian day. The time series NDVI ...
0
votes
0answers
35 views

Calculating raster values from center to edges to represent normal distribution

Edit for simplification/clarification: What I want to do is take a raster and calculate cell values from center to edges such that the center has an arbitrarily determined high value which decreases ...
1
vote
0answers
309 views

Trilateration Math Check

I'm trying to crate an indoor trilateration program working off of N BLE objects. Where I have any number of beacons in a room and my ipad can track its location within them to a sub meter degree of ...
1
vote
0answers
214 views

Trilateration issue

My program isn't making use of any geographical data, but I'm hoping that the users experience in the subject can help me with my current issue. The project I am working is trying to locate a user in ...
3
votes
1answer
98 views

T-shaped polygons

Is there any coefficient that can indicate T-shaped polygons ? Examples of T-shaped polygons :
4
votes
2answers
1k views

What formula is used for distance between 2 points in Google Maps?

What formula is used by Google Maps for calculating the shortest distance between 2 points (having their Lat, Lng coordinates)? Is it purely based on Haversine? Or is it something different? Is there ...
3
votes
1answer
505 views

How to calculate angle of polyline at its midpoint using Python/ArcPy?

Trying to calculate the angle of a line at its mid point using python; this will be used to display flow direction on a water network. I've developed this script, which works in terms of generating ...
1
vote
1answer
136 views

How to determine vector between two lat/lon points

For all the math geniuses out there...given two lat/lon points (point A and point B), what is the simplest way to find the vector needed to reach point B from point A. For example, the vector needed ...
3
votes
1answer
127 views

What are the set of projections that can be accurately georeferenced using polynomial 2?

Background I'm starting with a map from the internet (Encyclopedia Britannica) and georeferencing it using QGIS 2.0.1, I get really accurate georeference solution using polynomial 2 transformation: ...
2
votes
0answers
101 views

How to locate a house on the 3D Map correctly?

I've done my 3D map generation in WebGL/THREE.JS project and have an issue with the building locations. I have the data about building position ( its polygon ) from DB server, but first of all I want ...
0
votes
2answers
634 views

Detecting invalid polygons (self-intersecting or touching)

An invalid polygon can be defined as one that intersects itself, or one where the lines make contact, ie, the two shapes at the top of this picture. Given the XYPoints of a polygon, what logic ...
1
vote
1answer
104 views

math related sum distance problem (TSP content)

I hava an interesting problem related with GIS / MATH / TSP. If I calculate the distance between A and B on a x/y-style coordinate system it is obvious to use the following formula: ...
1
vote
1answer
185 views

Find items within a Bounding Box

Not 100% sure if this is the correct place to ask my question so I apologise if it isn't. Also, I have very limited experience with GIS systems, so please pardon my ignorance if some of my terminology ...
3
votes
1answer
183 views

Is it possible to solve Differential Equations in ArcMap and/or ERDAS Imagine?

I would like to know if it is possible to solve differential equations and run them directly in either ArcMap or ERDAS Imagine, similar to the raster calculator in ArcMap?
4
votes
1answer
637 views

How to sum or even perform more complex mathematical operations (multiply, add a constant, …) two GDAL grids?

I have two grids with same cell size, same starting position (top left) and same grid size. I want to sum the grids and create a sum grid as an result: e.g. grid A + grid B = grid C How can I ...
9
votes
3answers
1k views

Calculating mean slope: Harmonic or Arithmetic Mean?

I have to calculate the average upslope percent slope for a large dataset, the basic method is detailed here. However, I've begun to wonder if harmonic mean might be more appropriate than the ...
4
votes
1answer
973 views

Drawing Ellipse with OpenLayers

I am trying to draw ellipse on the client side using openlayers with some mathematical functions from drawing ellipse with svg. I have achieved drawing it but not rotation what I have written for ...
18
votes
3answers
2k views

How to calculate the intersection of 2 Circles?

I'm trying to figure out how to mathematically derive the common points of two intersecting circles on earth's surface given a center Lat/Lon and a radius for each point. Ex. Given: Lat/Lon ...
0
votes
3answers
379 views

Calculate 'Rectangle' Coordinates Given 2 Points and width [closed]

I want to create a rectangular polygon using two points as guides. So let's say a journey starts in Egypt and ends in London, my polygon should have 4 points: 10 miles further from London than Egypt ...
7
votes
1answer
591 views

Find the nearest point on a line

I have a line that exists between two latlon positions, and a point on a certain latlon position. What I want to know is what the nearest point on that line is (in respect to the other point). So a ...
1
vote
0answers
14 views

strange misplaced markers on the map [duplicate]

Possible Duplicate: place markers on the outline of a circle in google maps I used word Strange because I'm not expert in this area, and it really looks weird to me. I've already asked a ...
3
votes
1answer
304 views

How to place markers on the outline of a circle in google maps?

I have the center of a circle and it's radius and I need to place variable amount of markers on the outline/stroke of the circle. The distance between this markers should kept same, so if I have 8 ...
4
votes
0answers
281 views

Proper use of Modulus “%” operator in ArcMap [closed]

Objective: Gather pour points to define a specific-sized watershed. In this case, 1000 pixels. (for this thought exercise, watershed is to mean any point that flows through a pour point, regardless ...
1
vote
2answers
633 views

How to do Math within ArcMap Dynamic Text?

Is it posssible to perform any math on ESRI ArcMap dynamic text? For example I have the area of a SDE park layer's SHAPE.AREA, but it is in m2 because the layer is in NAD_1983_UTM_Zone_17N. I want ...
2
votes
1answer
411 views

Recreating A Lat/Long Grid Using a Specified Formula

I'm trying to recreate the Gridded Mercury emissions 2000 (0.5 x 0.5 degree grid) designed by the Arctic Monitoring and Assessment Programme. The file is in ASCII format, but without any coordinates. ...
7
votes
3answers
3k views

How to find a point half way between two other points?

I'm working on implementing the OSM Mobile Binary format for map data, and because it uses a 16 bit delta for each point along a way, it cannot represent a way if there is a large distance between two ...
4
votes
3answers
184 views

Math module VS PostGIS

I have a simple (and maybe stupid) question for you today. I have to compute intersection points between GIS polygons and imaginary lines I draw thanks to a script of mine... And I wonder if it would ...
4
votes
1answer
1k views

How to “calculate” distance-to-ground of all 18 OSM zoom levels?

Assuming I'm building a 3D solution with the "world" being mapped to global geo-data supplied by OSM / Cloudmade... think http://www.webglearth.com but with completely different goals and use-cases. ...
4
votes
5answers
6k views

Calculate midpoint from a series of latitude and longitude coordinates

I've got a series of longitude and latitude coordinates which represent a building outline e.g. -0.5485381346101759,53.2285150736142 -0.5482220594232723,53.22842450827133 ...
12
votes
3answers
2k views

Calculating the distance between a point and a virtual line of two lat/lngs

Please refer to the example and corresponding image. I would like to achieve the following: provide two locations (lat/lng), which are shown below as A and B. From this, a virtual line would be drawn ...
8
votes
3answers
168 views

Location storage and query algorithms. How do they work?

One of the most important aspects of a GIS-equipped database is that it provides the user with the capability to quickly query for all points within some arbitrary geographic area that match some ...
11
votes
4answers
522 views

Math and Stat for GIS and Computing

I am planning to do an advanced program in spatial science and engineering. It states as a requirement in the program, that the student should have a through understanding in math and statistics. So ...
6
votes
1answer
2k views

RMSE between two rasters step-by-step

Can anyone show how to calculate the RMSE (root mean square error) between following two rasters step-by-step and discuss on the obtained results' min and max values, and how to interpret it. Thanks a ...
7
votes
2answers
1k views

Determine angle down to horizon from different flight altitudes

I'm a pilot, not a GIS expert. What I need is a formula or a web site that I can supply the variables to answer my question. I need to know the angle down to the horizon from different flight ...
2
votes
1answer
353 views

How do I calculate curvature using GIS co-ordinates [closed]

I have GIS data for which I would like to calculate where curvature is present. Anyone has done this before, please help.