open data – Page 2 – Master of Spatial Analysis

Displaying Brooklyn’s Urban Layers by Mapping Over 200 Years of Buildings

Renad Kerdasi
Geovis Course Assignment
SA8905, Fall 2015 (Rinner)

Growth in Brooklyn
Located at the far western end of Long Island, Brooklyn is the most populous of New York City’s five boroughs. The borough began to expand between the 1830s and 1860s in downtown Brooklyn. The borough continued to expand outwards as a result of a massive European immigration, the completion of the Brooklyn Bridge connecting to Manhattan, and the expansion of industry. By mid 1900s, most of Brooklyn was already built up as population increased rapidly.

Data
The data in the time series map are from PLUTO, which is a NYC open data site created by NYC Department of City Planning and released in 2015. The data contain information about each building located in the boroughs, including the year the construction of the building was completed (in numeric 4 digits format) and the building footprints. The building years range from 1800 to 2015, there are some missing dates in the dataset as well as some inaccuracy in the recorded dates. The data are available in Shapefile and Windows Comma Separated format, found on NYC Planning website: http://www.nyc.gov/html/dcp/html/bytes/dwn_pluto_mappluto.shtml

The Making of the Time Series
To present the structural episodes of Brooklyn’s built environment, QGIS 2.10 was utilized with the Time Manager plugin. QGIS is an open source GIS application that provides data visualization, editing, and analysis through functions and plugins (https://www.qgis.org/en/site/about/). The Time Manager plugin animates vector features based on a time attribute (https://plugins.qgis.org/plugins/timemanager/). This tool was effective in presenting a time series of Brooklyn’s building construction dates.

To create the time series, the PLUTO SHP was downloaded and prepared by removing any unnecessary fields. The columns of interest are: FID, Shape, and YearBuilt. Because we are interested in the time column, the formatting must fit with QGIS Time Manager. QGIS Time Manager requires timestamps to be in YYYY-MM-DD format whereas the building dates in the PLUTO SHP are in a four-digit format. Therefore, the date in the dataset must be modified to fit the Time Manager format before it can be brought into QGIS.

In QGIS, Time Manager plugin must be installed first. The SHP can then be added into QGIS as well as other Shapefiles needed: roads, highways, state boundaries, etc. Note: to use Time Manager, the data must be in SHP format.

Once the data are added, the polygons (i.e. buildings) are styled based on age. This will be effective in distinguishing the oldest buildings from the newest. In QGIS, there are a large number of options available to apply different types of symbology to the data. The layer is styled based on the attribute Year Built, since the time series will show urban layers using building dates. Also, Graduated is chosen because features in the layer should not be styled the same way. The other data file, such as roads, highways, and state boundaries, are styled as well.

Once all the data are added and styled, it can be oriented and applied to the Time Manager plugin. To truly see the urban layers, the map is zoomed on the upper portion of Brooklyn. In Time Manager settings, the layer with building dates is added and the Start Time is the Year Built field, which includes the timestamp data. To get features to be configured permanently on the map, in the End Time option “No End Time” is selected. For animation options, each time frame will be shown for 100 milliseconds, and timestamp (i.e. built year) will be displayed on the map.

In the Time Manager dock, the time frame is changed to years since the animation will be showing the year the construction of the building was completed. The size of the time frame will be 5 years. With these settings, each frame will display 5 years of data every 100 millisecond. Playing the video will display the animation inside QGIS, and one can see the time scrolling from 1800-2015 in the dock.

Time Manager also enables you to export the animation to an image series using the “Export Video” button. Actual video export is not implemented in Time Manager. To play the animation outside of QGIS, various software applications can be used on the resulting image series to create a video file.

In addition, QGIS only allows users to insert a legend and title in the Composer Manager window. Currently, it is not possible to get the legend rendered in the main map window. One approach to generate a video with a legend is to create a dummy legend and add the image containing the legend into the PNGs that Time Manager produces. A dummy legend and a title for Brooklyn’s urban layers was created outside of QGIS, and added to each PNG.

Finally, to create a time-lapse and compile the images together, Microsoft Movie Maker was utilized. Other software applications can be used, including mancoder and avidemux.

Results

Link: https://youtu.be/52TnYAVxN3s

3D Hexbin Map Displaying Places of Worship in Toronto

Produced by: Anne Christian
Geovis Course Assignment, SA8905, Fall 2015 (Rinner)

Toronto is often seen as the city of many cultures, and with different cultures often come different beliefs. I wanted to explore the places of worship in Toronto and determine what areas have the highest concentrations versus the lowest concentrations. As I explored the different ways to display this information in a way that is effective and also unique, I discovered the use of hexbin maps and 3D maps. While doing some exploratory analysis, I discovered that while hexbin maps have been created before and 3D maps have been printed before, I was unable to find someone who has printed a 3D hexbin prism map, so I decided to take on this endeavor.

Hexbin maps are a great alternative technique for working with large data sets, especially point data. Hexagonal binning uses a hexagon shape grid, and allows one to divide up space in a map into equal units and display the information (in this case the places of worship) that falls within each unit (in this case hexagon grids). The tools used to create this project include QGIS, ArcGIS, and ArcScene, although it could probably be completed entirely within QGIS and other open-source software.

Below are the specific steps I followed to create the 3D hexbin map:

Obtained the places of worship point data (2006) from the City of Toronto’s Open Data Catalogue.
Opened QGIS, and added the MMQGIS plugin.
Inputted the places of worship point data into QGIS.
Used the “Create Grid Lines Layer” tool (Figure 1) and selected the hexagon shape, which created a new shapefile layer of a hexagon grid.
Figure 1: Create Grid Lines Layer Tool
Used the “Points in Polygon” tool (Figure 2) which counts the points (in this case the places of worship) that fall within each hexagon grid. I chose the hexagon grid as the input polygon layer and the places of worship as the input point layer. The number of places of worship within each hexagon grid was counted and added as a field in the new shapefile.
Figure 2: Points in Polygon Tool
Inputted the created shapefile with the count field into ArcGIS.
Obtained the census tract shapefile from the Statistics Canada website (https://www12.statcan.gc.ca/census-recensement/2011/geo/bound-limit/bound-limit-2011-eng.cfm) and clipped out the city of Toronto.
Used the clip tool to include only the hexagons that are within the Toronto boundary.
Classified the data into 5 classes using the quantile classification method, and attributed one value for each class so that there are only 5 heights in the final model. For example, the first class had values 0-3 in it, and the value I attributed to this class was 1.5. I did this for all of the classes.
The hexagons for the legend were created using the editor toolbar, whereby each of the 5 hexagons were digitized and given a height value that matched with the map prism height.
Inputted the shapefile with the new classified field values into ArcScene, and extruded the classified values and divided the value by 280 because this height works well and can be printed in a timely manner.
Both the legend and hexagonal map shapefile were converted into wrl format in Arcscene. The wrl file was opened in Windows 10 3D Builder and converted into STL format.
This file was then brought to the Digital Media Experience (DME) lab at Ryerson, and the Printrbot Simple was used to print the model using the Cura program. The model was rescaled where appropriate. My map took approximately 3 hours to print, but the time can vary depending on the spatial detail of what is being printed. The legend took approximately 45 minutes. Below is a short video of how the Printrbot created my legend. A similar process was used to created the map.

The final map and legend (displayed in the image below) provide a helpful and creative way to display data. The taller prisms indicate areas with the most places of worship, and the shorter prisms indicate the areas in Toronto with the least places of worship. This hexagonal prism map allows for effective numerical comparisons between different parts of Toronto.

Animating Toronto Parking Enforcement with heatmap.js

by Justin Pierre – Geovis course project for SA8905, Fall 2015 (Dr. Rinner)

Heatmap.js is a project developed by Patrick Wied to create heatmaps online using JSON data and javascript. It’s lightweight, free to use and comes with tons of great customization options.

For my geovisualization project for SA8905 I created an animated heat map of parking tickets issued in Toronto during the 24 hour period of May 1st 2014. Parking ticket data is supplied on the Toronto Open Data Portal.

Thursday May 1st, 2014 was one of the busiest days of the year for parking tickets. There were 9,559 issued in 24 hours. 6am was the safest time with only 25 tickets issued and 9am was the busiest with 1,451.

To create the heatmap I geocoded the Toronto parking ticket data using the city of Toronto street data with address ranges. About 10% of the records had to be manually geocoded to intersections, which was a time consuming process! Once I had the locations, it was simple to create a JSON object for each hour in excel, like this:

var h=[ {
 max: 100000,
 data: [
{lat: 43.667229, lng: -79.382666, count: 1},
{lat: 43.728744, lng: -79.30461, count: 1},
{lat: 43.778933, lng: -79.418283, count: 1},
{lat: 43.647378, lng: -79.418484, count: 1},

etc…

h is an array where each element is a JSON object containing the lats and lngs of each traffic ticket. The count is required for the heatmapping function and is always 1, unless you’re this driver:

Using heatmap.js is super straightforward. Initialize your web map in leaflet or openlayers (I used leaflet), configure some simple parameters:

var cfg = {
 "radius": .008,           //set for interpolation radius
 "maxOpacity": .8,         //set to .8 to show the basedata
 "scaleRadius": true,      //recalibrate radius for zoom
 "useLocalExtrema": true,  //reset data maximum based on view
 latField: 'lat',          //where is latitude referenced 
 lngField: 'lng',          //where is longitude referenced
 valueField: 'count'       //where is the numerical field
 };

Attach that to your heatmap object and point it at your datasource like so:

heatmapLayer = new HeatmapOverlay(cfg);
map.addLayer(heatmapLayer);
i=0;
heatmapLayer.setData(h[i]);

Remember that h[] is the array where the ticket data is stored and so h[0] is the first hour of data, midnight to 1am. This will create a static heatmap like this:

Now comes the part where we cycle through the hours of data with a setInterval() function:

setInterval(function(){ 
 i+=1;
 if (i>23) i=0;
 $( ".heatmap-canvas" ).fadeOut( "slow", function() 
   {heatmapLayer.setData(h[i]);
   heatmapLayer._draw();
   $( "#hour").html(i);
 });
 $( ".heatmap-canvas" ).fadeIn( "slow", function() {
 });
}, 2000);

Every 2,000 milliseconds (2 seconds) the page will fade out the heatmap layer, switch the data for the next hour and fade it back in. If the cycle has reached the end of the day it resets. The $( “#hour”).html(i) bit refers to changing the hour printed on the webpage itself.

You can check out the finished project at http://justinpierre.ca/tools/heatmap/ and be sure to let me know what you think at https://twitter.com/jpierre001.