Map panning and zooming methods

Following last week’s post on losing context with interactive maps, I wanted to consider the different methods of navigating an interactive map (i.e., panning and zooming) and how they might affect that issue, and while I’m at it look at other aspects of these methods, too.

A great place to start is the 2005 paper by my now co-mappers Mark Harrower and Ben Sheelsey called Designing Better Map Interfaces: A Framework for Panning and Zooming.* (A PDF is available on Professor Harrower’s web site.) In that paper they discuss criteria for evaluating panning and zooming methods, namely functionality and efficiency, and then go on to present and evaluate nine common methods of panning and zooming. With respect to my previous post, it is a lack of what they call “local-global orientation cues” that can lead to the “navigational trauma” of losing context.

Below are small demos of eight of the nine methods listed by Harrower and Sheesley, along with their thoughts and mine on functionality and efficiency as well as a word or two on the prior subject of maintaining context. (For simplicity I’ve left zooming out of most of those demos where it would be accomplished via separate interface widgets.)

Known sometimes as “slippy maps” (from OpenStreetMap?), maps with this kind of panning interaction are the standard these days in the big online mapping services from Google, Yahoo, Microsoft, etc.

Pros: No pesky tools or interface to deal with, and the action is natural and mimics real life manipulation of tangible objects.

Cons: High mouse mileage—you’ve got to move your mouse every bit as far as you want the map to move.

Context: There are no inherent orientation cues, so with this method alone you’d have to mentally keep track of the map’s movements. There is, however, an advantage of methods that directly jump from place to place.

You don’t see these a whole lot on maps, but they are of course very common in a lot of applications. What makes a scroll bar “smart” is that its size indicates the proportion of the document you’re currently viewing, and it disappears entirely if it’s not necessary.

Pros: Easily understood because they’re so common, and very efficient for traversing great distances.

Cons: You can only go in one direction at once. That’s fine for long written documents, but probably a nuisance for larger images and maps.

Context: Smart scroll bars do provide some local-global orientation cues by indicating how much and what portion of the map you’re looking at, but they don’t indicate what is actually around the area in view.

The idea here is that as you move your mouse away from the center of the map, the map moves in the direction of the cursor, and the farther it is from the center, the faster it moves. Off the top of my head I can’t recall seeing this a lot in interactive maps. What comes to mind first is a couple of the SimCity games, where a certain type of click would activate something like this type of panning.

Pros: Takes up no space on the screen.

Cons: It can be hard to control and can result in disorienting unintentional movement, and it becomes difficult to use the mouse for anything else.

Context: As with “grab and drag” you might be able to follow the movements, but with the map moving all the time (perhaps unintentionally), it’s probably pretty easy to get lost.

This is pretty straightforward: usually the arrow keys pan, and the plus and minus keys zoom.

Pros: The mouse is free for other purposes, and no screen real estate is required.

Cons: Users might not know that the functionality exists, and panning is restricted to four or possibly eight directions. Also, as seen in my demo, at least with certain web-based technologies, action is required to prevent the keystrokes from controlling the browser rather than the map.

Context: Pretty much like the slippy map, though perhaps worse depending on exactly how the map moves with the keystroke.

If I’m not mistaken, this was one of the several standard options for a click action in the old days of MapQuest. These days MapQuest still recenters under a single click but doesn’t zoom. Google, Yahoo, and Microsoft maps all zoom and recenter with a double click.

Pros: Combines two actions into one, and makes it easy and fast to get to a target that is on screen.

Cons: It’s no help getting to an off-screen target, and could result in unintentional movements if a user is just clicking on the map as a part of exploring. (I’m always clicking on non-interactive things and highlighting text for no reason while wandering through the internets.)

Context: You get where you’re going in steps, which perhaps makes it easier to see and recall context, but once again there’s nothing in particular that provides any orientation cues.

Navigator tabs or an interactive compass are directional buttons either around the map’s edges or grouped together somewhere in the interface. Clicking them typically moves the map by a set amount, although continuous movement is certainly possible. I think navigator tabs around the edges used to be common in online maps, but these days the major ones use the interactive compass style.

Pros: It’s obvious what the controls do.

Cons: Directions are limited, and if the map moves by predefined amounts, the user can’t necessarily achieve the desired view.

Context: No orientation cues here either, though again you are forced to step your way to where you’re going, at least permitting you to keep track of where you are.

A zoom box is something I feel like I see most often in GIS-like applications. Here you click on the map and draw a box, specifying the extent and location to which you wish to zoom.

Pros: Efficient and allows precise user control.

Cons: Works poorly for off-screen targets, doesn’t help with zooming out, and often requires first activating a tool.

Context: Much like the rest of them. No orientation cues, though you should at least have a rough idea of where you are within the whole since you were the one specifying the extent.

The navigator window is the most sophisticated of the panning and zooming methods presented here. A box in an overview map represents the current map extent. Panning can be accomplished clicking and dragging the box on the overview. Sometimes zooming is also incorporated by allowing the user to draw or resize the box.

Pros: Ridiculously efficient for browsing, as the entire map can be traversed by moving the mouse a short distance.

Cons: Can take up a lot of precious screen real estate.

Context: Finally, a method that provides good local-global orientation cues! With the navigator window you can always see what you’re looking at in the context of its surroundings, whether they be the entire map or just a larger area than currently in view. You won’t, however, gain any detailed information about the context, simply because of the navigator window’s small scale.

Yahoo Maps search interface

I was not about to make my own demo of the ninth method, specifying explicit coordinates or scale. This is basically what the major online mapping services do. You search for where you want to go (an address, a business, or whatever), and the map goes there. This, by the way, is what Harrower and Sheesley call “precise” navigation—knowing where you want to go and going directly there—as opposed to “fuzzy” navigation—browsing the map to find what you’re looking for.

Pros: Oh so efficient if you know what you want to find. Type, click (or enter), and you’re there.

Cons: To be most useful, the system and the data behind it have to be very flexible. Joe Cartographer can make a map that allows users to jump to a latitude and longitude, but he doesn’t have the resources to make an über-map like Google’s.

Context: It’s a wonderful way to use maps, but this really is the root of the problem we think might exist with losing context. You can find what you’re looking for, but this method gives you no indication of what’s around it or how you got there.

Now, most good maps of course employ more than one of these methods, ideally maximizing the pros and mitigating the cons. Google Maps, for example, uses six of the above: grab and drag, keyboard controls, zoom and recenter on click, interactive compass, navigator window, and specify extent (search).

It’s also worth noting that as a 2005 publication (effectively pre-Google Maps), the Harrower and Sheesley paper is already a bit dated in its list of common panning and zooming methods. A few updates and evolutions:

  • Zooming with the mouse scroll wheel. I’ve heard complaints, but personally I like the way Google et al. do this: when you use the scroll wheel, the point on the map under the cursor remains in the same spot on the screen as the map zooms in or out. By allowing you to anchor the map, perhaps this has some advantages for preventing “navigational trauma.”
  • Goolge Earth controls. The current Google Earth navigation control is like Interactive Compass 2.0. There are two: one that controls both rotation and tilt, and another that controls panning. Both allow complete freedom in direction.
  • Thanks to Chris of mundanemaps for showing this way of giving both context and detail, now possible with online map APIs. It’s like a magnifying glass but better: instead of providing just a close-up of a place upon clicking the marker, it shows a complete interactive map at a larger scale. It’s almost like an inverted navigator window. If you want, you can use the large map to keep the context while interacting with the smaller maps to view details.

*Mark Harrower and Benjamin Sheesley. “Designing Better Map Interfaces: A Framework for Panning and Zooming.” Transactions in GIS, 2005, 9(2): 77–89.

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14 Comments

  1. Great post, thanks for rounding all that up. I think the balance, as always, is between tools for power users and interfaces that are intuitive and easy to learn/discover. Ideally our map software would allow us to enable/disable each of these different methods as a user preference, but online it would be a pain to have to ask every time, of course.

    OpenLayers has a zoom box interface that’s worth playing with, but sadly it’s totally hidden. Once I heard it was there I definitely started using it a lot more. Try it on http://www.openstreetmap.org by shift-clicking and dragging to select an area.

    Tom Carden
    30 June 2008 @ 12:13pm

  2. Thanks for the comment, Tom. That zoom box is a good example of the trade-off: a good tool for the power user, but difficult to discover. I will admit that when it’s my decision, it’s probably that power user who’s going to lose because I’ll opt for something that’s as easy to use as possible without additional interface tools or options, so the OpenLayers solution for the zoom box is probably the type of compromise I’d make. But of course as with every interactive map, it really depends on the purpose and audience.

    Andy Woodruff
    30 June 2008 @ 6:31pm

  3. rad post. i’m going to use some of these references in an article i’m working on. thanks a million!

    Jamon
    1 July 2008 @ 10:14am

  4. thanks for the post andy. any chance you’d share some of the as AS3 code for these methods with us? ;)

    Anna Prentice
    20 July 2008 @ 10:03pm

  5. The actual code I used for those examples is a little too slapped-together for me to want to just give out (really, I bet half the function and variable names are variants on the word “mug”), but although I’m a bit too busy to get to it now, perhaps soon I can follow up with some sort of overview of how things work.

    Andy Woodruff
    24 July 2008 @ 5:23pm

  6. Control.Navigation() and Control.ZoomBox() instantiation malfunction?

    handan
    8 September 2008 @ 2:49am

  7. I’m just revisiting this post in the context of some Modest Maps examples I’m writing, and it occurs to me there’s one other control method that’s missing :)

    Rather than navigator tabs on the edge of the window, it seems like most online maps use and arrangement of arrow buttons and +/- buttons or a zoom slider.

    Some recent feedback we got on our hurricane maps complained that the controls weren’t in the ‘usual’ place. I wonder where that is?

    Tom Carden
    13 September 2008 @ 8:08pm

  8. Indeed, the direction tabs on the edges are more rare these days. I recall them more in older days of things like MapQuest, when the map in view was a single static image. The more common arrangement you note would be the “interactive compass” that the Harrower and Sheesley paper groups together with the navigator tabs. Not sure why I chose the less common style for my example, actually.

    Interesting about the hurricane maps feedback. (They’re fantastic, by the way!) It’d be nice to say there’s no correct or ideal solution for the panning and zooming interface, but it’s hard to defy the might of Google Maps and the other big boys!

    Andy Woodruff
    14 September 2008 @ 4:32pm

  9. Занимаюсь дизайном и хочу попросить автора http://www.cartogrammar.com отправить шаьлончик на мой мыил) Готов заплатить…

    Illerne
    14 October 2008 @ 4:32am

  10. Great post, was there a follow up post giving an overview?

    Andrew Wall
    1 July 2009 @ 6:07am

  11. Great demonstration!!
    I actualy have to do something exactly like your “navigator window”. Could you tell me how you code that with AS3? Is it opensource?

    thanks a lot!

    Benoit,

    Benoit
    24 August 2011 @ 1:33pm

  12. Great stuff…. it would be more helpful if u could give me least once example code..

    Ramesh Belludi
    24 February 2012 @ 2:18am