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On a tangent, I do feel most GIS systems and applications still use 2d maps instead of a 3d globe, which I think could do with some rethinking. Working with glo

On a tangent, I do feel most GIS systems and applications still use 2d maps instead of a 3d globe, which I think could do with some rethinking. Working with globes could eliminate the whole apparatus of projections, and I guess would simplify a lot of calculations.. but there seems to be much resistance to this idea.

fsloth 6y ago
The majority of land data that is used as the backbone for land registry, lotting, road planning, etc etc is stored... ...as datasets based on 2D map projections. And different places have different projection systems. 2D projections will be with us for a long time.
growlist 6y ago
It would certainly be interesting as an exam question, for example, to compare 2D and 3D for what it would reveal about each, but in the end it's all about choosing an appropriate model for the task at hand. I'd therefore suggest that pitting 2D against 3D is actively choosing to set up some kind of battle that doesn't actually exist in reality - most of the time there is nothing to be added to an analysis by choosing to store data in 3D, and 2D simplifies all parts of the chain i.e. capture, storage, processing, output etc. I'd strongly reject the idea that but for resistance we'd all be in a wonderland of 3D GIS. People in industry just pick the best tool for the task at hand, and that's almost always 2D.
- billfruit 6y ago
  Perhaps it is not only the resistance of practitioners/ legacy of experience and data in 2d, but also the unavailability of a decent tech stack for 3D GIS.
  - growlist 6y ago
    But why, if completely 3D GIS would be so super awesome, do you think that that decent tech stack doesn't exist? The answer is that for the vast majority of applications of GIS, 3D is just an unhelpful distraction. I don't want to upset you, but I really think you are not speaking from a position of knowledge if you think otherwise (I have a couple of degrees in Geography including one in GIS specifically, plus 15+ years' experience in the field).
tomgp 6y ago
It’s still being projected onto a screen though so you’re still using a projection. There are some pretty extreme trade offs you accept when using a orthographic ‘globe’ projection, not least of which is that you can’t see half the planet for any given moment.
- billfruit 6y ago
  I don't exactly get this argument. It is not only about what you see on screen, I was talking about geographic operations like spatial queries being executed on the globe rather than on a projected 2d surface.
  - growlist 6y ago
    > spatial queries being executed on the globe But it's perfectly possible to create geodesically-correct buffers, for example - such as you might see when calculating ballistic missile range over thousands of kilometres - in a 2D projection, and indeed this has been available for decades. And we have plenty of global models, such as WGS 84: https://en.wikipedia.org/wiki/World_Geodetic_System https://en.wikipedia.org/wiki/World_Geodetic_System So what exactly are you talking about?
    - billfruit 6y ago
      So do you think there is no benefit if we can avoid projections entirely? Also won't using 3d make working with great-circle paths easier?
- mxfh 6y ago
  Since it's three.js you can plug in as many rasterizers, as you have eyes for XR, which makes it distinct from a proper 2D implementation, which would have to fake the arcs: https://observablehq.com/@armollica/globe-with-lofted-arcs https://observablehq.com/@armollica/globe-with-lofted-arcs The philosophical question here: is a stereopair of 2 near-orthographic (near side general Projections still a projection, or is it only a globe, if it's tactile? In general I would prefer the CanvasRenderingContext2D way to handle this simple display use case, since it looks cleaner and more predictable across devices on screen and doesn't keep your gpu busy when not animating anything.
marcosdumay 6y ago
You aren't eliminating projections. You are just settling into the one kind of projection given to you by a lower level layer.
mxfh 6y ago
It's not about resistance, it's about compatibility and use case scope. In 3d a lot of assumptions about the shape of earth and location above ground become non-trivial very quickly. When it comes to precisions required in surveying, local systems are usually prefered, because you can ignore the whole thing of shifting global datums due to plate tectonics. In essence:a patchwork of local references frames per plate is prefereable to a single global one, when having to work with measurements over the time of decades. Which happen to also work reasonably well in 2D when projected. https://www.openstreetmap.org/user/StephaneP/diary/390290 https://www.openstreetmap.org/user/StephaneP/diary/390290 https://news.ycombinator.com/item?id=20460596 https://news.ycombinator.com/item?id=20460596
GuB-42 6y ago
In GIS you are not dealing with true 3D data. Only the surface of the earth matters. Using 3D coordinates would be extremely wasteful. So you need a projection to map the surface data onto a sphere and another one to map the sphere onto the 2d screen. No way around it. Using the same projection for display as for data saves a transformation. Usually it is some variant on Mercator because it is the one people are most familiar with. In the end unless you are starting to think about true 3D (multi-story buildings, caves,...) thinking of a "3D globe" is just a bit of projection math that doesn't fundamentally change the problem.

fsloth 6y ago

The majority of land data that is used as the backbone for land registry, lotting, road planning, etc etc is stored... ...as datasets based on 2D map projections. And different places have different projection systems. 2D projections will be with us for a long time.

growlist 6y ago

It would certainly be interesting as an exam question, for example, to compare 2D and 3D for what it would reveal about each, but in the end it's all about choosing an appropriate model for the task at hand. I'd therefore suggest that pitting 2D against 3D is actively choosing to set up some kind of battle that doesn't actually exist in reality - most of the time there is nothing to be added to an analysis by choosing to store data in 3D, and 2D simplifies all parts of the chain i.e. capture, storage, processing, output etc. I'd strongly reject the idea that but for resistance we'd all be in a wonderland of 3D GIS. People in industry just pick the best tool for the task at hand, and that's almost always 2D.

billfruit 6y ago
Perhaps it is not only the resistance of practitioners/ legacy of experience and data in 2d, but also the unavailability of a decent tech stack for 3D GIS.
- growlist 6y ago
  But why, if completely 3D GIS would be so super awesome, do you think that that decent tech stack doesn't exist? The answer is that for the vast majority of applications of GIS, 3D is just an unhelpful distraction. I don't want to upset you, but I really think you are not speaking from a position of knowledge if you think otherwise (I have a couple of degrees in Geography including one in GIS specifically, plus 15+ years' experience in the field).

tomgp 6y ago

It’s still being projected onto a screen though so you’re still using a projection. There are some pretty extreme trade offs you accept when using a orthographic ‘globe’ projection, not least of which is that you can’t see half the planet for any given moment.

billfruit 6y ago
I don't exactly get this argument. It is not only about what you see on screen, I was talking about geographic operations like spatial queries being executed on the globe rather than on a projected 2d surface.
- growlist 6y ago
  > spatial queries being executed on the globe But it's perfectly possible to create geodesically-correct buffers, for example - such as you might see when calculating ballistic missile range over thousands of kilometres - in a 2D projection, and indeed this has been available for decades. And we have plenty of global models, such as WGS 84: https://en.wikipedia.org/wiki/World_Geodetic_System https://en.wikipedia.org/wiki/World_Geodetic_System So what exactly are you talking about?
  - billfruit 6y ago
    So do you think there is no benefit if we can avoid projections entirely? Also won't using 3d make working with great-circle paths easier?
mxfh 6y ago
Since it's three.js you can plug in as many rasterizers, as you have eyes for XR, which makes it distinct from a proper 2D implementation, which would have to fake the arcs: https://observablehq.com/@armollica/globe-with-lofted-arcs https://observablehq.com/@armollica/globe-with-lofted-arcs The philosophical question here: is a stereopair of 2 near-orthographic (near side general Projections still a projection, or is it only a globe, if it's tactile? In general I would prefer the CanvasRenderingContext2D way to handle this simple display use case, since it looks cleaner and more predictable across devices on screen and doesn't keep your gpu busy when not animating anything.

marcosdumay 6y ago

You aren't eliminating projections. You are just settling into the one kind of projection given to you by a lower level layer.

mxfh 6y ago

It's not about resistance, it's about compatibility and use case scope. In 3d a lot of assumptions about the shape of earth and location above ground become non-trivial very quickly. When it comes to precisions required in surveying, local systems are usually prefered, because you can ignore the whole thing of shifting global datums due to plate tectonics. In essence:a patchwork of local references frames per plate is prefereable to a single global one, when having to work with measurements over the time of decades. Which happen to also work reasonably well in 2D when projected. https://www.openstreetmap.org/user/StephaneP/diary/390290 https://www.openstreetmap.org/user/StephaneP/diary/390290 https://news.ycombinator.com/item?id=20460596 https://news.ycombinator.com/item?id=20460596

GuB-42 6y ago

In GIS you are not dealing with true 3D data. Only the surface of the earth matters. Using 3D coordinates would be extremely wasteful. So you need a projection to map the surface data onto a sphere and another one to map the sphere onto the 2d screen. No way around it. Using the same projection for display as for data saves a transformation. Usually it is some variant on Mercator because it is the one people are most familiar with. In the end unless you are starting to think about true 3D (multi-story buildings, caves,...) thinking of a "3D globe" is just a bit of projection math that doesn't fundamentally change the problem.