Visualizing Freshwater Resources: A Laser Cut Model of Lake Erie with Water Volume Representations

Author: Anna Brooker

Geovisualization  Project Assignment @RyersonGeo SA8905, Fall 2018

Freshwater is a limited resource that is essential to the sustenance of all life forms. Only 3% of the water on earth is freshwater, and only 0.03% is accessible on the surface in the form of lakes, streams, and rivers. The Great Lakes, located in Southern Ontario and along the US border, contain one fifth of the surface freshwater. I wanted to visualize this scarcity of freshwater by modelling Lake Erie, the smallest of the Great Lakes. Lake Erie is 6th largest freshwater lake in the world, but is has the smallest water volume out of the Great Lakes. I decided to create a laser cut model of the lake and use water spheres to represent its proportion of the world’s surface freshwater resources. I used the infographic from Canadian Geographic for reference.

Process:

  • Retrieve bathymetric imagery and import into ArcScene
  • Generate contours lines for every 20m of depth and export them each into individual CAD files
  • Prepare the CAD files in an Adobe Illustrator layout file to optimize them for laser printing
  • Paint and assemble the laser cut layers
  • Create spheres out of clay to scale with the model

The following images show the import of the bathymetric imaging and contour retrieval:

The bathymetry data used was collected in 1999 by the National Oceanic and Atmospheric Association and comes in a raster file format. They were retrieved from Scholar’s Geoportal. I used a shapefile of the Lake Erie shoreline from Michigan’s GIS Open Data as a mask to clip the raster imaging to only the extent of the lake surface. I then created 20m contours from the raster surface. I exported each of the 3 contour vectors into individual shapefiles. These were added to the scene and exported again as CAD files to be able to manipulate them in Adobe Illustrator and prepare them on a template for laser cutting.

The screenshots above show the template used for laser cutting. The template was downloaded from the Hot Pop Factory homepage. Hot Pop Factory is the service I used for laser cutting the plywood layers. I used their templates and arranged my vector files to reflect the size I want the model to be, 18″x7″. I added the rectangles around each contour to ensure a final product of a rectangular stacked model. I then sent this to the Factory for cutting. The photos below show what I received from Hot Pop.

Lake Erie is incredibly shallow with maximum depth of 64m. In order to show the contours of the lake I needed to exaggerate the depth. Limited by the thickness of the materials available to me, the final model had an exaggerated depth of approximately 130% at its deepest point. The final result of this exaggeration allowed me to create three layers of depth to Lake Erie and make it more visually engaging. I included as a part of my model a flat cut out of Lake Erie, which is what the model would have looked like if I had not exaggerated it.

The water volume spheres were created using a material called porcelain clay. This air dry medium has a slightly translucent finish. I stained the clay with blue oil paint so that it would intuitively represent water. The size of the spheres is based on the information in the Canadian Geographic infographic linked in the introduction to this tutorial. The diameter of the spheres was made to scale with the scale bar on the models. A limitation with this model is that the scale bar only refers to the lateral size of the lake and spheres, and does not refer at all to the depth of the model.

The photos above show the final product. The photo on the right shows the scale bar that is included on both parts of the model. I painted the interior layers in blue, the top two layers in the same shade. The third layer was slightly darker, and the deepest layer was the darkest shade of blue. I chose to paint the layers in this way to draw attention to the deepest part of the lake, which is very small area. I attached the layers together using wood glue and laid them beside each other for display.  I painted the 3D and 2D models in slightly different hues of blue. The 2D model was made to better match the hue of the water spheres to visually coordinate them. I wanted the spheres to be distinct from the 3D model so that they would not be interpreted as being representative of the water volume of an exaggerated model.

 

Creating a Toronto City Ward Model Using Laser Cut Acrylic

by Selasi Dorkenoo

SA8905 Cartography and Geovisualization Fall 2018

To better understand characteristics of the new municipal electoral wards in the City of Toronto, the new 25-ward boundary shapefile provided by the City of Toronto was converted to vector format and laser cut into five translucent sheets of acrylic. Each piece is engraved with the ward ID. Laser cutting allows the puzzle to not only fit together with precision, but also visualized the demographic census data using redundant symbology: opacity (lightness) and height.

Ward boundaries were retrieved from Toronto Open Data Catalogue and imported into ArcGIS Desktop. The model was designed to be cut into 16 in x 8.5 in sheets of 3mm acrylic, including legend items and a scale bar. Features in black (below) represent pieces that were laser cut and features in red represent laser engraving on a piece. Using layout view, the design was exported as a vector (.ai) file and sent to Hot Pop Factory for their laser cutting services.

Once the acrylic was cut, a magnet was super-glued to each piece below the engraved ward IDs. The magnets used were about 6mm in diameter and 2mm in thickness. Magnets were also attached to the scale bar and legend items. Using a magnetic white board as a base for the model, the pieces were stacked and the model itself was complete.


Demographic data at the ward level was retrieved from Toronto Open Data Catalogue as well. Once joined to the ward boundary file, a set of choropleth maps including population density, visible minorities, unemployment rate and average personal income were created. A maximum of five bins can be used to classify the data in each map since only five sheets of acrylic were laser cut for the model.

A catalogue of these maps was printed and packaged with the ward model. Users can browse through the catalogue and select which variable they wish to map. Using dry erase markers they can write the necessary cartographic elements on the mapped area (i.e. legend labels and title).

Use of a Laser Cutter to Create a 3D Bathymetric Chart

Mallory Carpenter,  SA8905 Geovisualization Assignment, Fall 2015

Bathymetric, or depth data collected about oceans and other water bodies are typically displayed in one of two ways –  as a bathymetric chart, or as a depth raster.  New technologies such as 3D printers and laser cutters allow for the better communication of depth data. Laser cutters in particular allow for “etching,” which can simultaneously communicate topographic data.  This allows the viewer to better situate themselves in the landscape.  Examples of this can be seen here and here.

A fjord is a coastal feature formed by glaciers.  Typically, they contain steep vertical sidewalls, and deep basins separated by shallow sills (ridges of bedrock which rise to depths of less than 50 m).  Mapping Nachvak Fjord in 3D, located in the Torngat Mountains in Labrador, will help to better illustrate the unique bathymetric features.

The basic process is this:

  • Collection and processing of bathymetric data into useable raster format.
  • Importation of the raster data into GIS software.
  • The creation and export of contour data as vector files to secondary graphics.
  • The division of contours into separate layers, and the addition of any graphics for “etching.”
  • Different colours in the vector file are used to differentiate between etching and cutting.

The screenshots below show the bathymetric data collected between 2003 and 2009 by the Canadian Hydrographic Service and ArcticNet. The data are available for free for download from the Ocean Mapping Group website. The spatial resolution of the data is 5×5 m with a vertical accuracy of 1 m. The data ranges in depth from 211 m to 1 m.  Contours were created at 20 m intervals, smoothed and exported as vector files.
The data used for etching the topographic map on the top layer are a product called CanVec, which is downloadable for free from Geogratis. The contour interval was reduced to 200 m to improve visibility. Extraneous shapefiles such as points were removed.

Nachvak1

The data were manipulated in iDraw (a Mac-based vector graphics program) to smooth out overlapping lines and crop to an appropriate area as shown in the following screenshot.

Nachvak2

The laser printer has a 2 x 4 foot printing bed.  In order to save materials and cutting time, layers need to be nested in the bed space, colour coded for cutting and etching, and exported as either a PDF or SVG.  Each contour makes up a layer – with a solid rectangle for the base, and the topographic information etched into the top layer.  The following screenshot shows two cutting surfaces, each with 5 map layers.

Nachvak5

nachvak4

The laser cutting was done at the Danforth Tool Library (http://torontotoollibrary.com), out of 1/4 inch Birch Plywood.  They were cleaned (the cutting produces soot), stained, and glued together with carpenter glue.

Nachvak5

Initial plans included the use of etching to detail habitat and substrate information.  Time and finanical constraints limited the amount of etching work that could be done.  Additionally, if the project were repeated it could be worth either using thinner materials, or increasing the contour interval.  The slope on the side walls is so steep, and the fiord so narrow that the fine details are hard to see in the final version.

Nachvak7