Google Maps- Report a problem

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Below is a brief summary detailing my first experience with Reporting a problem in Google Maps…

On April 25th, I used the “Report a problem” tool at http://maps.google.com/ to report an obvious street label error on the Dunn Memorial Bridge in Albany, NY.


View Larger Map

Yes, Google Maps evidently has the Dunn Memorial Bridge in Albany crossing the Hudson River from Illinois to Nebraska!

I reported the issue using Google’s “Report a problem” tool, which was fairly intuitive, but not as exciting as making an actual edit in Potlatch 2. I received an auto reply from Google confirming they received the notification and issued a Google Maps Problem ID (790F-846D-6339-B85E). So far, so good!

On April 28th, I received the following email update from Google:

Correcting a simple labeling error this obvious isn’t “easy for us to fix at this time”? Really Google… really!

Yet another reason to switch2osm!

 

Leaflet Users Map

Posted by & filed under Leaflet, maps, sqlite.

Show me the map: http://users.leafletjs.com/

I have been working on a few projects lately using the excellent Leaflet JavaScript mapping library from Cloudmade. Leaflet is a relatively new project that has an active group of contributors, a loyal user base and has been generating a lot of buzz in the community.

Inspired by the Quantum GIS Community Map, I decided to hack together a site showing Leaflet users… on a Leaflet map of course. This project was to be my first GitHub Repository as well. I have been slowly learning Git, as GitHub has become the main version control platform for many popular open source projects. All the cool kids in the FOSS4G realm are embracing GitHub (Leaflet, OpenLayers, GeoExt) and if you want to keep up with these projects, you best create a GitHub account post haste!

I had a few prerequisites going in to this thing; it had to be lightweight and simple, reusable for future projects, and built on solid components that followed similar principles. Initially, I settled on the following architecture:

The logic is quite simple since we are only dealing with points.

Insert New User:

The user visits the map, which initially zooms to fit the extent of all the existing markers. They zoom into their local area (or use Leaflet’s built-in browser geolocation function), click to drop a marker on the map, and fill in a short form (which captures the lat/lon of the click event in hidden fields). This info then gets inserted into the SQLite database of users via a simple little PHP script.

Drop Existing User:

I did want to include some mechanism to allow users to edit their information, but I didn’t want to bother with a system for authentication, usernames, passwords, etc, etc. The application does not collect any sensitive data (other than emails), so I just generate a random 6 digit token that gets inserted with the user’s info and emailed to them upon insertion. To “edit” your info, you simply remove your marker by passing your email and token to another simple little PHP delete script and adding a new marker with your updated info.

Map Users:

The markers are loaded from the database by a PHP script that fetches the data as an associative array and echoes out JSON. This JSON data gets parsed with jQuery’s  $.getJSON function and a for loop is used to add the markers to a Leaflet FeatureGroup. Nothing to it but to do it!

UI Overhaul:

After the initial release of the site, I received some great feedback and decided to overhaul the user interface to support a better range of browsers and screen resolutions. I scrapped jQuery UI and went with the Twitter Bootstrap library. The Bootstrap interface and navbar may see familiar as this toolset has become super popular in recent months (notice my website redesign).

Current version: http://users.leafletjs.com VS Original version: http://users.leafletjs.com/V1.html

Let me know what you think and if you use Leaflet, I encourage you to join the Leaflet Users Map!

 

Fun with the Open Data Kit

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I’ve recently rediscovered the Open Data Kit project and have been having a lot of fun playing around with this suite of tools designed for building mobile data collection solutions. ODK is a Google sponsored project, which is supported by the University of Washington’s Department of Computer Science and Engineering. It appears mainly aimed at humanitarian projects in the developing world, but looks like it may be creeping into the business sector as well.

The basic ODK workflow:

  • Design a data collection form
    • ODK forms follow the XForms XML standard and can be built using ODK’s web-based build application. There are several other tools available for building these forms, and they can also be built manually with a simple text editor.
  • Install the ODK Collect app on your Android smartphone
    • This is a generic mobile data collection app that transfers data between your phone and your database server.
  • Configure the ODK Aggregate server to manage your collected data
    • This is a Java based application, which can be deployed on Google’s App Engine infrastructure, or configured locally to connect with a MySQL or PostgreSQL database.

GIS Potential:

ODK has the potential to fill a crucial gap that has existed for years between low-end recreational GPS units (think eTrex) and high-end GPS data collectors (think Trimble). Recreational GPS units are dirt cheap and fairly accurate these days, but they lack any sort of sophisticated data collection capabilities. You get waypoint name and description fields, and a selectable symbol if you are lucky, but this just won’t cut it for most GIS projects where data integrity is paramount. Most recreational GPS units are built on closed platforms (Garmin, Magellen) while the industry standard for high end units seems to be  Windows Mobile (ArcPad, TerraSync).

Smartphones however, offer reasonably cheap hardware paired with sophisticated open operating systems. Most have decent cameras and GPS sensors and they are connected to the web by default. There are tons of GPS and mapping apps already out there, but what we really need is a generic application that works with our custom data dictionaries or forms- and this is where ODK shines!

Tips, Tricks, and Hacks:

As a Google project, ODK works seamlessly with App Engine and Fusion Tables, which is cool in and of itself, but hardcore GIS requires more tweaking. A Java application that uses PostgreSQL just screams out for PostGIS and GeoServer integration! Here’s what you need to know to get this system up and running…

Prerequisites:

  • Android smartphone (for ODK Collect)
  • Java servlet containter (for ODK Aggregate)- tested on Jetty and Apache Tomcat 6
  • GeoServer 2.1.0 or higher for SQL Views (can use database views with < 2.1.0)

Lessons Learned:

  • Play around with the App Engine install first to see what you can do with ODK before you dive into configuring locally
  • Download the configuration wizard from the Google code repository: http://code.google.com/p/opendatakit/downloads/list
  • ODK Aggregate can run in the Jetty servlet container that ships with the GeoServer windows service installer, but I would recommend deploying on Tomcat…
  • Make sure you create your intended ODK postgres database using the PostGIS template!
  • Setup your ODK database as a GeoServer data store and make your layers as GeoServer SQL Views
  • Use the following bit of PostGIS magic in your SQL View to transform the lat, lng coordinates in the ODK database into GeoServer friendly WKB geometries: ST_GeometryFromText(‘POINT(‘||”FORM_FIELDNAME_LNG”||’ ‘||”FORM_FIELDNAME_LAT”||’)', 4326) AS “the_geom”
  • You will have to manually enter the layer bounding box values as you probably won’t have the full extent of your data populated in your table yet. To be safe, you can enter: -180, -85.051, 180, 85.051, which covers the globe avoiding the poles.

ODK + PostGIS + GeoServer + Leaflet:

An exercise in open source mobile GIS data collection: http://geoserving.net/odk_geoserver

GeoServer, ArcMap, and Dropbox

Posted by & filed under ArcGIS, dropbox, hacks, postgis.

Realtime editing of GeoServer data stores is easy with PostGIS and QGIS. You can wow your friends by making edits on the desktop and watching them reflect live on your web mapping applications! But what if your friends are using ArcMap (insert punchline here)?

Forgetting about silly things like SDE and the “Data Interoperability Extension”, one is left with few options. No direct editing of PostGIS, no WFS-T support… One is left desperately waiting in anticipation for zigGIS 3.0.  A simple workaround to avoid having to perform multiple ETL processes or FTP’ing shapefiles from desktop to server is to use Dropbox.

  • Install dropbox on your GeoServer box
  • Set up a shapefile directory data store on your dropbox folder
  • Share this folder with your fellow collaborators
  • They load the shapefiles from the shared directory on their local machine and edits are automatically pushed to the GeoServer box and updated in your output data streams

Nothing to it! Use this information cautiously, and remember that concurrent editing against shapefiles can potentially get you into trouble…

jQuery Mobile + OpenLayers + NYSDOP

Posted by & filed under mobile gis, openlayers.

Some exciting things have been taking place over the past few weeks…

The OpenLayers Mobile code sprint in Lausanne appears to have been a huge success. The new Mobile Demos speak to the great progress that was made over a single week.

While I was in Florida on vacation last week, I received an email from the NYS GIS listserv that the (ancient) New York State Digital Orthoimagery Application was (finally) being replaced with a (functioning) application called New York State Orthos Online. I was happy to see that the state didn’t fall for the old ESRI flex viewer template, but actually came up with a nice application built on the ArcGIS JavaScript API. We can finally browse and download imagery without having to open Internet Explorer!

I decided to take the fruits of all this labor and build a new mobile web application that may or may not be useful to others out there. The result is the NYS Orthos Online Mobile application (NYSOOM). NYSOOM is basically a touch-optimized mobile version of the NYS Orthos Online site. I took the ArcGIS REST services hosted by the state and plugged them into the OpenLayers jQuery Mobile example that was a product of the code sprint in Lausanne. So if you are curious about the Empire State, break out your smartphone and peruse through the entire imagery collection (1994-Present). The current URL of the application is http://geoserving.net/nysoom, but if there is any interest I may move it to another domain.

Let me know what you think!

PS- You can check out the application on your desktop using Google’s Chrome browser.

A recent CHA project

Posted by & filed under maps, php, postgis.

The Watervliet Interactive Mapping Application is a web-based GIS platform built entirely on Open Source components and technologies, including PostGIS, OpenLayers, and GeoEXT.

This has been a fun little project and a departure from the norm- as there is no GeoServer backend powering this application. All of the vector data is stored in a PostGIS database and fetched as needed via a few custom PHP scripts. Data is exchanged in GeoJSON format and the larger datasets (parcels, buildings) are limited by the user viewport extent.

This method works great for a municipality with a relatively small geographic footprint and dramatically simplifies the system architecture.

WAPPStack & PostGIS 5 Minute Install

Posted by & filed under maps, php, postgis.

I’ve been working on building some lean and mean web mapping applications lately.  While I’m a huge fan of GeoServer, some projects just don’t require the additional overhead of a GIS server.  While GeoServer really is a phenomenal application, I often find myself getting tripped up trying to build applications with PHP that have to interface with GeoServer sitting on Apache Tomcat.  You can get around this using proxy scripts, reverse proxies and packages like PHP/JavaBridge, but if you’re just building a web map and you really don’t need all the OGC services, you can probably get away with just using PostGIS and writing some simple scripts to fetch your data.

They key to this approach is to take advantage of the PostGIS output functions (ST_AsGML, ST_AsGeoJSON, ST_AsKML).  If you are working with large datasets, you’ll want to limit the amount of data you throw at the browser by registering a ‘moovend’ event, grabbing the viewport coordinates, and returning only the features that fall within the current map extent.  For something like tax parcels, you will have to set tight scale thresholds so the user is forced to query at a reasonable extent.  You’ll know if you screwed something up when you try to force someone running IE6 to load a 50MB KML file in their browser and it blows up in their face!

I’ve put together some quick and dirty documentation  on setting up an Apache + PHP + PostGIS development environment using the excellent BitNami WAPPStack package for Windows.  The documentation covers:

  • Downloading and installing the BitNami WAPPStack
  • Configuring Apache and PostgreSQL to run as services
  • Installing PostGIS in the WAPPStack package
  • Configuring PostgreSQL and phpPgAdmin to allow access from outside IP addresses

WAPPStack & PostGIS 5 Minute Install Documentation

Website Updates and PostGIS

Posted by & filed under Uncategorized.

You’ve probably noticed that I’ve updated my website again! This comes on the heels of upgrading to a new web host- http://www.a2hosting.com. I have used A2 in the past and have been very pleased with their services and support. A2 is based out of Ann Arbor, MI and offers several Linux hosting options at decent prices. What sold me on A2 was their explicit support for PostGIS- the spatial database extension for PostgreSQL. All of their hosting packages come standard with MySQL and PostgreSQL databases, and to enable PostGIS you simply submit a support ticket telling them what database you want it installed on.

If you’ve ever had the pleasure of playing around with PostGIS before, you’ll know why I’m so excited about this. If not, I highly suggest you head over to OpenGeo’s Intro to PostGIS workshop. Simply put, PostGIS integrates all the spatial functions and processing tools you could ever ask for within a (free) relational database. This means that you can run spatial queries and geoprocessing tasks directly against your data store without having to mess with any bloated middleware (think Arc…). PostGIS is the go-to data store for all the popular open source GIS packages and even plays well with ArcGIS! Best of all, the spatial functions are exposed as SQL queries- this means you can build powerful GIS web applications on top of PostGIS with a scripting language such as PHP.

Image courtesy of OpenGeo (http://workshops.opengeo.org/postgis-intro/introduction.html)

GeoExt Popups

Posted by & filed under open geoportal.

Fresh tax parcels deserve fresh popups! SLC OGP GetFeatureInfo requests are now displayed in beautiful GeoExt popup panels.

You can have multiple popups open at once, unpin them from their feature and expand to fit the screen. Check it out!