The abstract study of topics encompassing quantity, structure, space, change, and other properties
12
votes
2answers
263 views
Bilateration - 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 ...
11
votes
4answers
430 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 ...
9
votes
3answers
204 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 ...
8
votes
3answers
1k 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
147 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 ...
7
votes
2answers
709 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 ...
7
votes
1answer
226 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 ...
6
votes
3answers
1k 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
157 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
199 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 ...
4
votes
1answer
705 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
0answers
161 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 ...
3
votes
1answer
1k 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 ...
3
votes
1answer
112 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 ...
2
votes
5answers
2k 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
...
2
votes
1answer
74 views
Differential Equations in ArcMap or ERDAS Imagine
I would like to know if it's possible to solve differential equations and run them directly in either ArcMap or ERDAS Imagine, similar to the raster calculator in ArcMap.
Thanks
J
2
votes
1answer
228 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. ...
2
votes
1answer
66 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 ...
2
votes
1answer
332 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.
1
vote
1answer
25 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 ...
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 ...
0
votes
3answers
209 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 ...
0
votes
2answers
149 views
Doing Math On ESRI 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 ...
0
votes
0answers
52 views
Long/lat to tile row and column for a certain layer on EPSG:900913
I have a bunch of XYZ layers rendered in OpenLayers. I want to give a lon, lat and Z value and the system would return the X and Y location of the tile of that XYZ layer.
I found the following 2 ...
0
votes
0answers
29 views
Need guidence about project [closed]
I am currently studying Remote Sensing and GIS. I previously completed a 4 year degree program in Mathematics.
I would like help in selecting my final thesis and a basic project work topic for the ...
0
votes
0answers
25 views
Mathematics behind converting scale to resolution using 4326? [duplicate]
Possible Duplicate:
Mathematics behind converting scale to resolution?
I have a question similar to the one I posted here. In this case I want to determine how to calculate the resolution ...
