Day two of the Olympics and the world records are tumbling. Tearing our eyes away from the action in Rio, we’re seeing an Olympiad of a different kind: Donghong’s marathon experiment in 3-d modelling with robotics. Our visit today revealed the fourth iteration of the experiment in carving a topographic model from plywood. Donghong is now satisfied that he has achieved an acceptable compromise between fine workmanship and efficiency.
One of the most interesting and confronting aspects to come out of this whole project arose fairly soon after I transferred the elevation data set into Stephen and Donghong’s hands. Donghong had transposed the data into a 3-d topographic image on the screen. In this image the landscape of the Mackay catchment looked dramatic, with sharp peaks resembling the mountains in southern China. The reason it looked like this is that he had exaggerated the elevations to make an otherwise dull, seemingly featureless land mass into something more ‘readable’. This was a surprising turn of events for us – we hadn’t anticipated that the ‘true’ topography of the catchment would not convey the visual information we wanted people to see. By increasing the ratio of the elevation relative to the area of land represented, the land forms became more legible. Somehow it seemed deceptive to be doing this. It then raised the question of mapping in general. How accurate are maps? What story are they telling? You only have to think of the difference between the Mercator projection maps and the Peters projection maps to realise that there seems to be no universal standard for mapping.
As it turns out, the exaggerated elevations have been decreased to something closer to the actual elevations. This was for practical reasons in the end – less wood will be used and the job therefore completed more quickly. Instead of six sheets of 15mm ply in height, the model will now require only three sheets. Additionally, Donghong has decided to use the 2mm router bit instead of the 1mm bit for the finer work, as this will also increase productivity. The result won’t be as fine, but is acceptable for our purposes.
Over the weekend I made some sandbag weights which will hopefully be useful when it comes to gluing ‘islands’ of land cut from the second sheet of ply on to the base sheet. At this point I’m imagining that it will be like a giant jigsaw puzzle. Tomorrow, all being well, I’ll help Donghong with the gluing. He anticipates finishing the model on Wednesday. Once it’s ready to be put in our hands, we’ll have to seal it will something to prevent moisture from warping the plywood.