Все вопросы: [gis]

137 вопросов

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8
голосов
9ответов
11208 просмотров

Where can I find a city/neighborhood database?

Where can I find a database of cities and neighborhoods using MySQL? I'm only interested in US areas. Price doesn't matter. The database must help identify locations by ZIP code. I've already got a database showing cities and states, but I need to find surrounding neighborhoods as well. I saw g...

3
голосов
1ответов
186 просмотров

Spatial data types in MS SQL 2008 and Subsonic 3 - workaround available?

Using the latest version of Subsonic (3.0.3) it doesnt appear to me that the geometry or geography data types are implemented as of October 09. My questions are: if and when is this support likely to be added? does anyone have a workaround to support operations on simple geography types at th...

8
голосов
2ответов
6064 просмотров

SQLite + SpatiaLite problems

I'm trying to access a SpatiaLite from C# using System.Data.SQLite provider. When I try to load the SpatiaLite extension, I always get the System.Data.SQLite.SQLiteException: SQLite error The specified module could not be found. error, even though the spatialite's dll has been copied to the b...

3
голосов
5ответов
2727 просмотров

Creating custom Google (or OpenLayers?) maps

I'm currently working on a project which maps items to a physical location within a building. We have a map created in our GIS system (ArcGIS), and are able to resolve items to the appropriate shape ID on this map. We want to create a web map using one of the APIs such as Google maps or Open Lay...

35
голосов
6ответов
38789 просмотров

How do you know what SRID to use for a shp file?

I am trying to put a SHP file into my PostGIS database, the the data is just a little off. I think this is because I am using the wrong SRID. The contents of the PRJ file are as follows: GEOGCS["GCS_North_American_1983", DATUM["D_North_American_1983", SPHEROID["GRS_1980",6378137.0,298.257222101]...

0
голосов
1ответов
1302 просмотров

Furthest distance between any two points with GeoDjango

I have a collection of Point objects. I want to find the furthest distance between any two points. Imagine a circle enclosing all of these points. I want to know the diameter of that circle. How can I do this in GeoDjango? edit: this is what I have so far: >>> r=Route.objects.get(pk=1)...

7
голосов
6ответов
8102 просмотров

How to round a decimal to the nearest fraction?

Not sure if that is the right way to ask this or not but here is the problem. Given a latitude of 26.746346081599476, how do I find the number 26.75 as the 16th greater than the number and 26.6875 as the 16th lower than the number? 26.0 26.0625 26.125 26.1875 26.25 26.3125 26.375 26.4375 26.5 2...

1
голосов
2ответов
1686 просмотров

Overview of how to develop LBS/GIS app in Java

I need to develop a location based extension to an existing app that will allow users to see all other users that are around them (within a fixed aerial distance). The existing app was developed using Axis (Web services) + Spring + Hibernate + MySQL. Requirements are: Java framework (preferab...

6
голосов
2ответов
2393 просмотров

Help plotting Geographic Data in R using PBSMapping and Shapefiles

Using O'Reilly's Data Mashups in R as inspiration, I'm trying to plot a handful of addresses on a shapefile of Salt Lake County, Utah found here. I have data frame geoTable: > geoTable address Y X EID 1 130 E 300 S 40.76271 -111.8872 1 2 875 E 900 S 40.74992 -...

3
голосов
3ответов
2375 просмотров

What is the Best Development platform for GIS application?

Reviewing a new GIS product development requirement and its in a requirement gathering phase. This application needs to run on a Desktop and some part of the application on a mobile device which then can sync to the desktop or the server. This product will deal with imagery, defining boundaries, ...

2
голосов
4ответов
1805 просмотров

Closest grid square to a point in spherical coordinates

I am programming an algorithm where I have broken up the surface of a sphere into grid points (for simplicity I have the grid lines parallel and perpendicular to the meridians). Given a point A, I would like to be able to efficiently take any grid "square" and determine the point B in the square ...

10
голосов
5ответов
4760 просмотров

Where to get Terrain Data - both free and paid?

Where can you get terrain data? What resolution data can you get for free? What resolution data can you get when you buy the data? How much is that data? I found this site that has free terrain data. The resolution is 30m x 30m. Is that the best that can be found for free?

3
голосов
2ответов
932 просмотров

How do I utilise longitude/latitude values efficiently in Mysql?

Thanks to Wikileaks, here in the UK we can now access our longitude and latitude co-ordinates for each post code wikileaks postcodes uk IMPORTANT. Do not use this data in public applications - There's concern that the data has been deliberately corrupted and you could be held as being in breach o...

7
голосов
1ответов
10401 просмотров

rescaling ranges

for example i have two ranges (1) 0 to 3 (2) 10 to 15 in range (1) i have numbers between 0 and 3, where 0 is minimum and 3 is maximum value...(it has also values 1 and 2)... now i wanted to rescale both ranges (1) and (2) to range 0 to 1. Can yo...

7
голосов
3ответов
5366 просмотров

PROJ.4 library and OSGB36

hope you are well I am trying to convert lat/long coordinates to OSGB36 x and y using the proj.4 library. Has anyone else successfully done this? I need to fill the srcPrj4String and destPrj4String variables, e.g. string srcPrj4String = "+proj=longlat +ellps=WGS84 +datum=WGS84 +no_defs"; strin...

2
голосов
1ответов
1823 просмотров

Calculating bounding grid coordinates to a user click on google maps/google earth

I have a requirement to calculate the centroid or geodesic midpoint of when a user clicks in between the lat/long grid crossing. The crossing forms a square in most parts of GE and sometimes elongated rectangles. This is due to the shape of the earth of course. I'm looking for a valid mathema...

1
голосов
2ответов
2339 просмотров

How can I draw a road using bing maps api?

Is it possible to draw a road using bing maps js api? Ideally I would supply two georeference points and the trajectory/road would be always on the same road. Basically, I want to highlight a road.

8
голосов
6ответов
16582 просмотров

Encoding problems with ogr2ogr and Postgis/PostgreSQL database

In our organization, we handle GIS content in different file formats. I need to put these files into a PostGIS database, and that is done using ogr2ogr. The problem is, that the database is UTF8 encoded, and the files might have a different encoding. I found descriptions of how I can specify th...

1
голосов
3ответов
422 просмотров

Idea Wanted: Raster Online Map (Possibly with ESRI API and some geoprocess model)

(I hope this is a valid question) As I stated in my title, I'm looking for a fairly easy to moderately easy idea for some sort of online raster analysis map. I'm familiar with ESRI and their really awesome API, as I'm hoping to tackle something on that front. I'm also open to using the mapstra...

0
голосов
1ответов
444 просмотров

Why are my ESRI:Tool items having their images reset when I select any other tool on the page?

In my default.aspx page, I have some ESRI tools (and some commands) in a toolbar, so something like this. <ToolbarItems> <esri:Tool ClientAction="MapPoint('Map1','%toolbarItem%',false,'crosshair') DefaultImage="~/images/default_tool.gif" EnablePostBack="True" JavaScriptFile="" ...

8
голосов
6ответов
4242 просмотров

Do you know any free satellite imagery for GIS?

Do you know any imagery where I can get satellite images of places for free? I have a terrain editor which uses GIS data for visualizing heightmaps but I want to texture them with satellite image. I hope some of you can provide some sources?

2
голосов
2ответов
1508 просмотров

tools for viewing TIN files

is there any free open source tools available for viewing TIN (triangular irregular networks) files( which i got from LAS (Lidar data) file...)? thanks!

2
голосов
4ответов
2206 просмотров

Extracting descriptive information from a LiDAR cloud (.las files)

I have .las (lidar data) file, now I wanted to know the size of it, for example how long it's width and height in kilometers. How is it possible to retrieve these kind of info?

0
голосов
2ответов
340 просмотров

looking for open source tools

Do you know any tools available for the conversion of LAS (LIDAR data) into Voronoi diagrams or TIN (triangular irregular networks) available? Or can anyone can suggest how to do it in arcgis?

24
голосов
6ответов
25638 просмотров

Calculating area enclosed by arbitrary polygon on Earth's surface

Say I have an arbitrary set of latitude and longitude pairs representing points on some simple, closed curve. In Cartesian space I could easily calculate the area enclosed by such a curve using Green's Theorem. What is the analogous approach to calculating the area on the surface of a sphere? ...

3
голосов
2ответов
2181 просмотров

ArcGIS Flex API: Convert a screen point to a MapPoint

Using the ArcGIS Server Flex API, is there a way to convert mouse coordinates on the screen or the a map control to spatial coordinates in the map? It seems like there's functionality to convert map points to screen points, but a function for converting in the other direction seems weirdly absent.

3
голосов
2ответов
820 просмотров

Determining if a point is on a road

If I have a polyline that describes a road and I know the road width at all parts, is there an algorithm I can use to determine if a point is on the road? I'm not entirely sure how to do this since the line itself has a width of 1px. thanks, Jeff

28
голосов
7ответов
14712 просмотров

How to calculate distance from a point to a line segment, on a sphere?

I have a line segment (great circle part) on earth. The line segment is defined by the coordinates of its ends. Obviously, two points define two line segments, so assume I am interested in the shorter one. I am given a third point, and I am looking for the (shortest) distance between the line a...

2
голосов
1ответов
1127 просмотров

tatukgis, save & load layer properties

If someone have some experiences with TatukGIS developer kernel product, can you explain how to programmatically save and load layer properties like in their free TatukGIS viewer product? The environment i use were Delphi 7 and BDS 2006 thanks Edit, this code don't work: var lyrPeta: TGIS_...

2
голосов
4ответов
617 просмотров

GIS: line_locate_point() in Python

I'm pretty much a beginner when it comes to GIS, but I think I understand the basics - it doesn't seem to hard. But: All these acronyms and different libraries, GEOS, GDAL, PROJ, PCL, Shaply, OpenGEO, OGR, OGC, OWS and what not, each seemingly depending on any number of others, is slightly overwh...