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creating purposely distorted maps

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#1
kay

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Hello, everyone. I have one question I wish to ask you. I am still not sure about it so I decided to talk to you all. I am wondering if you have the same experience as this case and if this kind of situation happens often...


Here is a story...
When making a map, would you distort your map purposely?
For example, your map is projected in US state plane and making a map of Massachusetts. To make your map extent square, would you like to scale the map horizontally by 50%?

After scaling your map only horizontally to 50%, would you still like to keep the georeference information (location information) correctly so that you may be able to plot point later.


The example above may be a bit exerggerated. However, Let's say you are making a trail map. The extent of the trail lines are 200 km wide (east-west) and 50 km (north-south direction). In this case, would you like to stretch your map vertically so that the map will "fit" in the "space" in the poster where the subway map to be displayed. Then.. if there are new trails created in the future, you have to add the new trails. Because of this, would you like to keep the georeference information with this stretch version of the trail map?


For those examples above, I am aware that there are problems.
1) cannot measure distance correctly.
2) cannot measure area correctly.
3) cannot measure the direction between two point correctly (angle etc.)

In the cartographic world, maps are the representation of reality. We try to illustrate things from the real world as close as possible to the one in the real world. (is my English ok to describe what I am going to try to say here?)

However, I have seen several cases that maps are purposely distorted for the graphical reason such as to fit in the space for the display, to emphasize some of the interests on the map etc...

This may be totally depending on what to be understood by the viewer. But I am not sure if it is good to distort maps purposely...unless I am making subway maps and I am 100% sure that user do not use the map for scaling and directional purpose...


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So... I am wondering if you have made any distorted maps and if you do it often. If so, could you share some examples and reasons to create "purposely distorted" maps?

I will look forward to your messages!

Thanks in advance,
kay

#2
Hans van der Maarel

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Essentially every map is distorted in some way (though I think that's not what you're referring to).

Anyway, yes, I have sometimes distorted my maps. Most recently on a project where I was making a base map for a weather website (buienradar.nl). In order to match the doppler data feed that was to be projected on top of my base map, I had to make it as a Plate Carree and then scale it horizontally by about 50%. This actually turned out quite well and of course was necessary due to the client requirements.

On the Oolaalaa globe chairs (here and here I made gores in polyconic projection, then slightly scaled them to compensate for stretching of the fabric.

Thinking of really distorted maps, subway maps come to mind. They have their pros and cons, but you can still use them for their primary goal: navigation.
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#3
frax

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I like to think of it as all maps are purposely distorted, it is just a matter of degrees. You are talking about the spatial aspects, but we are also simplifying, exaggerating and reducing the representation of the actual content - presenting it with simplified lines and discrete classes.
Hugo Ahlenius
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#4
DaveB

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It depends on a number of factors. I think there can be useful distortion, for example, scaling up some parts of a map to emphasize and focus on some area and/or allow for more detail. This could start to get into cartograms like ones where Washington, D.C. and some of the smaller states are made larger so you can see colors in a choropleth map.
If the map is for navigational or other types of distance/areal measurement that's another story. So I wouldn't distort a trail map, but a map of trails that is intended for illustrative purposes might be okay somewhat distorted. Distorting by 50% to fit some display proportions seems to me like painting pictures a certain color to match decor. Is it still really art; is it still really a map? Does it stop being a map at some point and start being something else (illustration, graph, ??) Maybe one definition could be utility - does it still serve one or more of the purposes of a map? (and what are the possible purposes that would qualify as "mappy"?)
Dave Barnes
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#5
kay

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Hello, Hans, Hugo, Dave and everyone. Thank you so much for your comments to my question. I am sharing your comments with my friends here. We are having a big discussion about this...

Could I ask you more questions? When you make a "squeezed" version of map, do you "squeeze" the map after all the georeferenced information are imported/added to your map? You can put colours etc before/after squeezing the map. I am thinking I am right (correct me if I am wrong...).

Once you completed your squeezed version of map, would you like to 'recycle' the map? For example, using the squeezed version of the map as a base map, then would you like to add some "georeferenced" layer on to the squeezed map? For example, if you create a volcano distribution map with the volcanic activity information (i.e. eruption), if any mountain on your map area starts to erupt, then you might want to add a new layer with this information. Even though the map is squeezed, the map 'techncially' has lat-long (or easting-northing) information so that any georeferenced layer/data can be plotted onto the squeezed version of the map.

What do you think of 'maintaining georeference information' of the squeezed map?? I understand that any map is 'distorted' in any way. But any projection has its pros and cons in terms of the accuracy or minimizing distortion of the map. Or.. should I just simply think the "squeezed" map as if it is a 'new projection/coordinate system'?

I will look forward to see your comments on this topic :)

Thanks a lot!!
Kay

#6
Dennis McClendon

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I think we're talking about completely different things here. Deliberate distortion and georeferencing really don't belong together in the same workflow.

Other than the distortion done for projection, a stylized map or distorted map in the sense we're discussing would not use GIS for any part of its production. It would be done by tracing features by hand, simplifying them each time and subtly moving features for the sake of the diagram's clarity. Or it might be done by conceptualizing the features of a city or region and then drawing them from memory.

Distorting a map of Tennessee so it fits into a square frame is so repugnant to cartographic tradition that I don't think any of us would willingly do it. We would look for a different solution to the problem, such as breaking it into two stacked maps or a birds-eye view from one end.
Dennis McClendon, Chicago CartoGraphics
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#7
ProMapper

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This is a great discussion on assigned or derived accuracy. A map is a 2D representation of a 3D earth, thus inherently we are introducing some errors or approximations to do that. But then we say the map is accurate to so and so extent but it happens within the approximated projected frame.

Now there is one peculiar property of map, may be assumed or otherwise, that it is presumed to have just one scale. Whereas a graph can have different vertical and horizontal scaling, I have not come across a map with similar attributes. But if we make such a map with different scaling on the two axes, will we lose the right to call it a map? I think, no, it will still be a map, because we still can get the right co-ordinates after a bit of mathematics, though not correct direction. And this would be the case if you scale the map down on either x or y axis.

And if you read the properties of some of the projections, then again we find that some keep accurate directions, others may keep accurate scaling, and some others would be great for accurate area calculations but you can not get all the attributes in any one of them. So you used to select projection based on the end use of the map before the advent of on the fly change in projection with today's computers.

So in the ultimate analysis if a representation can be attributed to some mathematical equation, may be different in different axes, and we call it a map. And if we can call it a map, then adding more layers with the same equation is also possible and may be even amendments of the features.

Anu
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#8
natcase

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As ProMapper points out, all these discussions are pretty theoretical to most of us, as the disproportional distortion of two different map axes is not usual or desired in a network map, or at least in the sort that we are used to.

I can envision an interesting sort of map based on a single linear route, with the surrounding land and connecting routes distorted to conform to that line, and compressed to allow the strip map to show more features. Sort of a modern Peutinger Table. I don't see any reason that GIS software couldn't (theoretically) be used for that, especially if the linear route is essentially straight to begin with.

The important thing to ask, to avoid the horror Dennis describes ("Chile's too tall. Squash it."), is: Does the distortion serve the meaning of the map, or the convenience of the mapmaker/publisher?

Nat Case
INCase, LLC

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#9
kay

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Hello, Dennis, Anu, and NatCase. I found your comments really interesting. I am sharing your comments with my friends here. Thank you so much for posting your message.


This "squeezing a map" technique happens due to the layout/graphic limitation. (at least to me it has happened only with the graphical reason). It was due to the "space" available for the map on the magazine or the product which the map will be displayed on and to make the map "esthetically nice".... After I created maps with the minimum error and optimum accuracy (in terms of spatial information), I really did not like the way that some other people (like my client) squeezing the maps so that my maps can technically fit in the space available in the publication. (Personally that was a sad moment :( They change the space specification for the publication after I created maps. The solution they made to the publication was "squeeze maps" so that they can fit them! )

Then, what happened was that they wanted to add some new information to the squeezed map. The new information is a good GIS dataset with "geo-perfect" (I just created a new terminology). The clients thought that it is easy to add those new GIS layers onto the squeezed map because my original maps before squeezed are georeferenced. Of course, since it is squeezed, all the georeference information was totally lost. The map had to be stretched to the original extent, then plot the new GIS layers. (If they want, they can squeeze back again!!)

This may be just simple personal preference.. that I do not want to have the map squeezed or stretched for the graphical or non-cartographic reasons.... especially if the map will be updated with geo-perfect GIS datasets in the future...
I understand that every map has "pros and cons" in terms of accuracy with the projection or coordinate system used in the map. If the squeeze map can be treated as one of the "coordinate systems" (like you can explain the spatial information by equation), it might make sense.

... I am still thinking... hmmm...




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