The abstract study of topics encompassing quantity, structure, space, change, and other properties
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 ...
0
votes
0answers
47 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 ...
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
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 ...
9
votes
3answers
202 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 ...
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 ...
4
votes
1answer
196 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 ...
12
votes
2answers
258 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 ...
0
votes
3answers
208 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
225 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
111 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
160 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 ...
0
votes
2answers
148 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
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 ...
2
votes
1answer
227 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. ...
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
703 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. ...
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
...
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
146 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
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 ...
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 ...
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 ...
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.
