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This is tricky for two reasons: first, limiting the points to a circle instead of a square; second, accounting for distortions in the distance calculations.
Many GISes include capabilities that automatically and transparently handle both complications. However, the tags here suggest that a GIS-independent description of an algorithm may be desirable.
To ...
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This question has been converted to Community Wiki and wiki locked
because it is an example of a question that seeks a list of answers
and appears to be popular enough to protect it from closure. It
should be treated as a special case and should not be viewed as the
type of question that is encouraged on this, or any Stack Exchange
site, but if ...
24
I maintain the GPSTest app on Google Play, which is open-source on Github.
I'm actively interested in adding Galileo support in the app, but to do this I need to know what IDs the Galileo satellites show up as in the Android platform. And, this requires that there be some agreement between Galileo hardware manufacturers of those IDs - see Is there an ...
23
Here are the results of my brief research on this Issue:
ArcGIS runtime for Android. Seems to be oriented towards showing ArcGIS Server's Mapservices. It can show data in an offline mode, by storing tiles in the compact cache storage format, or by using tile packages.
OSMDroid A component which can be used to show data from Open Street Maps when on-line, ...
18
There are a huge number of devices to choose from, and it is difficult to broadly say that one family of device are more precise than others. It is better to compare accuracy based on real life tests. However, there are a few things to consider:
Chipsets. Dedicated GPS, and Smart Phones use a chipset to actually perform the GPS calculation. The accuracy ...
16
I saw a study at New Mexico State comparing an HTC G1 and a Trimble Juno. You might want to check it out. Here are the study's accuracy test results:
13
I did an offline map using the ESRI Android SDK and a custom tile layer. I used an ArcGIS server to generate a tile based map cache, then inserted those tiles into a SQLite database and query them based on row and column from there. It works great and if you need custom maps end to end, it is a very usable method.
package com.main.utilinspect;
import java....
13
A few ideas come to mind for building your geospatial programming credentials:
Create a legacy of solutions and answers on GISse and Stack Overflow.
You will notice that many people on GISse creatively and wisely use
this forum to further their freelance work.
Create a web page or blog to show potential employers what you
know. Some of my favorites, and ...
12
Almost all of the web maps use a Web Mercator (Auxiliary Sphere) projection (WKID 3857). The parameters represent the coordinates for the edges of the viewing window. For example, were the coordinate system WGS84, the envelope for displaying the whole earth would have the following parameters:
XMin: -180 XMax: 180
Ymin: -90 YMax: 90
The reason the ...
11
Implemented for Javascript:
var r = 100/111300 // = 100 meters
, y0 = original_lat
, x0 = original_lng
, u = Math.random()
, v = Math.random()
, w = r * Math.sqrt(u)
, t = 2 * Math.PI * v
, x = w * Math.cos(t)
, y1 = w * Math.sin(t)
, x1 = x / Math.cos(y0)
newY = y0 + y1
newX = x0 + x1
10
There was a QGIS Android project as part of this year's Google Summer of Code. Marco Bernasocchi was the author, and although it is largely a work in progress, he has managed to get the basics working on an Android tablet. Just search QGIS Android and you'll come up with several links to mailing list posts, his blog, and download links.
For a proper useable ...
10
The best accuracy you are going to get with a phone or tablet device is 20-30 meters. So you have to ask yourself what is the purpose of your GPS? If you intend on navigating back to the asset in question, do you really want your users within 20-30 meters, is that accurate enough for what you are attempting to capture.
What the higher end GPS receivers give ...
10
The correct implementation is:
public static void getLocation(double x0, double y0, int radius) {
Random random = new Random();
// Convert radius from meters to degrees
double radiusInDegrees = radius / 111000f;
double u = random.nextDouble();
double v = random.nextDouble();
double w = radiusInDegrees * Math.sqrt(u);
double t = ...
10
Google has built their own vector map rendering engine based on OpenGL ES version 2:
https://developers.google.com/maps/documentation/android/start#requiring_opengl_es_version_2
Here's a link about OpenGL ES on Android:
http://developer.android.com/training/graphics/opengl/index.html
OpenGL lets you leverage the underlying power of the GPU and get ...
9
Ok, with some initial issues cleared out the task is relatively simple.
Scale, prepresented as f.ex 1:50000 means that one unit on the map corresponds to 50.000 units in the real world.
For a paper map printed a scale of 1:50000 this means that 1 meter on the map corresponds to 50.000 meters in the real world, or to make it easier: 1 cm on the map ...
9
I think the way that we create mapping applications is changing fast and the key to success in this industry is being ahead of that curve.
For example 10+ years ago when we wanted a blog we get a shared hosting solution, download a blogging platform like Wordpress or Movable Type install it on the server, buy a domain name, install a theme, bang our head ...
9
In short, yes - differential GNSS is now possible on Android, and, as of Android P (on supported devices), real-time kinematic (RTK), or carrier-phase measurements, are also possible.
The May 2018 Google I/O video "How to get one-meter location-accuracy from Android devices (Google I/O '18)" has a really good high-level explanation of the current state on ...
8
I just happened across another published study on this. Paul Zandbergen, 2009, Accuracy of iPhone Locations: a Comparison of Assisted GPS, WiFi, and Cellular Positioning. Transactions in GIS, 13(s1): 5-26. (PDF, 1mb)
They found median errors of 8 m with GPS-assisted 3G iPhones, down to median 47 m errors for WiFi, and median errors of 600 m (!) for ...
8
Quantum GIS for Android is one option.
http://android.qgis.org
Here is more info: http://www.opengis.ch/android-gis
8
Well, most people say OsmAnd is the best for Android. Lacking further details, I can't judge on your particular case. You need to know what features you want:
an app for end users or for mappers?
support for smartphone or tablet?
online or (fully) offline?
routing with different profiles?
POI search, address lookup?
open source / free / commercial app?
...
7
I have developed an application with offline maps for Android. The only free tool you would want to use is OSMDroid, otherwise ESRI. OSMDroid API is identical to Google's, so in case you want to switch from one to another, it's a breeze.
Check out this post, with a sample of how to integrate Google Maps into OSMDroid (it also gives you an idea how to use it ...
7
For offline maps using OSM data i find three libraries very much useful.
osmdroid : I use this library if i have to work with tiles that are in mbtiles format that i generate using tilemill. There is a bonus library for routing called osmbonuspack that adds lots of routing and POI functionality to this library.
mapsforge: I use this library when i need to ...
7
We have noted that with even some of the more noteworthy (commercial quality not retail) tablet makers, the GPS is not strong enough for central regions of Australia or when there is any kind of interference. Whereas say GETACS maintain a connection even when indoors. Cold boot times can also be in the double digit minutes for the tablets too.
This may be ...
7
Yes, you can use custom tiles with Android Maps API v2 - you can see a fully working example in our OpenTripPlanner for Android app on Github. (You can also download the app directly from Google Play)
We support the following tile providers:
LyrkOpenStreetMap
MapQuestOpenStreetMap
Mapnik
CycleMap
Google (normal, satellite, hybrid, terrain)
Our ...
6
I have recently been pursuing research in the same area as you, and have found that there are not currently any open source mobile GIS APIs around that would be suitable to building a client application specifically supported for Android. I did come across BeeGIS but have not had an opportunity to spend any time with it.
Additionally you can refer to this ...
6
Many cell phones and tablets will also use Wi-Fi data to assist their location fix. Google has a huge database of wireless access points and their locations, when the phone's Wifi is turned on it will check nearby wireless APs and use that to narrow down your location quickly. It's the same idea as using a cell tower to locate you, but a Wifi network's range ...
6
I would recommend a different strategy, that consists on using the Java library JTS Topology Suite, which is open source software.
By using the class WKTReader you can get, for example, an instance of the MultiLineString class from the WKT you have. This class has methods to get the coordinates you need.
6
There are a lot of options for collecting GPS point information on Android; I'm experimenting with several of them but none work terribly well - my use case is a bit tough, though, as I'm working out of low-flying Cessna aircraft and need constant GPS positions and to be able to instantly record a correct GPS position together with a note.
OpenDataKit: ...
6
I think the difference is likely due to the way that the Android phone with a GPS, and the iPhone using 3GS, are determining their location.
I am not sure about all Android phones, but it is likely that they are all using similar GPS for location purposes. This could be verified if you provided the similar models that you tested with. Anyway, the point is ...
6
One quick and dirty way uses a recursive spherical subdivision. Beginning with a triangulation of the earth's surface, recursively split each triangle from a vertex across to the middle of its longest side. (Ideally you will split the triangle into two equal-diameter parts or equal-area parts, but because those involve some fiddly calculation, I just split ...
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