Wednesday, November 16, 2011

Blog Break

I'm downing tools for a while but I'll be back 2nd week in December.

Google, Bing and OSM Maps: Train Station Symbolization

As part of my research for last weeks blog looking at how the three maps in the title handled symbolization with zooming, I had a look at some other locations in London.  The one that stuck out for me in terms of usability was Clapham Junction Train station at a low altitude zoom level.  This is a local station of mine and also happens to be the busiest station in the UK with over 100 trains an hour.  With so many passengers it makes sense that it should be mapped well.

The User's Needs when Zoomed In:  What is a general user looking for if they access a web map of this station?   If they are zoomed in close then chances are they are searching to answer these questions:

  1. Where is a station entrance with temporary parking? - I want to drop off someone by car.*
  2. Where is a station entrance handy for me?  - I'm getting to the station by bus/bike/foot?* 
  3. Where do I find food/drink/toilets/cash machine?
If they are changing trains at Clapham they will probably follow the station signs rather than looking at a web map so 'where is the platform I need?' doesn't get onto the list. 

Entrances and Exits are Key: So from a user's point of view I think the primary information that a map of this scale should show are the station entrances and exits.  If the user question is [3] then they still want to know about exits/entrances since often services are ouside the station and they will have to get in and out.  Using the above list it seems to me that the map could also usefully show temporary parking, bus stops, cycle racks, food outlets, toilets and cash machines.  However, the symbols showing these services should be secondary in visual impact to the entrances.

Let's see how the map providers fare in meeting these user needs:

Entrance locations: Before we begin the review we need to understand a little about the entrances to the station.  On the Open Street Map below I have added the four entrances to the station as red squares.  Its also important to know that the Brighton Yard entrance (bottom) is relatively new compared to the others.

Open Street Map of the Station:

First up, Open Street Map is packed with detailed information.  All the entrances are marked except Brighton Yard, however, they are symbolized weakly as dotted red lines and are difficult to pick out.  Services are marked on the map at many locations although I note that food outlets on the platforms and the access bridge are missing (I've now added them myself, because that's the point of Open Street Map).  There is no opportunity to click symbols and access further information.

Whilst Open Street Map has done well in terms of having the information available, my problem with this map is that it shows too much.  Most of the information is there but by packing all the data onto the map it becomes visually complex and the entrances are not emphasized.  A particular problem is the rail tracks: all the lines and sidings are shown but the location of these has no use for the average user as they will be navigating within the station guided by signs within the station.  Also, the dashed line symbolisation just doesn't work when the lines are packed together.

I discussed the 'too much' information problem in a previous post.

Google's Map of the Station:

Google's map is far clearer when compared to the Open Street Map but important information is missing and the symbolisation is confusing.  It shows roads and bus stops clearly but other services aren't well marked.  Entrances to the station are missing.  The multiple rail lines have been reduced to two which show the general directions of the lines leading out from the station - much better symbolisation.

My main problem with this map is that rather than use a polygon and a single marker to show the station (see last weeks discussion), Google has a confusing group of 3 markers.  You would be mistaken for thinking the station was quite small and in three separate locations.  In fact it's one large station that covers most of the above map, as you can see from the Open Street Map.  Click the rail station symbol and you are not linked to anything to do with the station but see information about the nearest buses.  Very odd.

Bing Map of the Station:

Bing's map is similar to Google's in terms of clarity:  Few train lines are shown, roads are clear and easy to see.  Bing also uses a single marker at the main St John's hill entrance which is logical and an improvement on Google's map.  When clicked this station symbol links to a route calculator which is more sensible.  

However, the other entrances are not marked and no services are marked.  At this zoom level I would expect at least some services marked and the lack of entrances is a real issue.

Conclusion:  I've outlined why I think at this scale of map, the key information users need about Clapham Junction station is the location of the entrances.  The maps vary in how many entrances they mark but none of them show all of them with the required level of emphasis IMHO.

Looking at other data that could be usefully marked on the map; Open Street Map has the most detail but it is presented in a visually complex way.  Bing maps goes to the other extreme with a very clear map but showing little useful information.   Google's approach of mixing some service information on a relatively clear map represents the most sensible approach but they have used some very odd symbols in the process.

*Obviously 'entrance' could be replaced by 'exit' in these questions for journeys going in the other direction.  For clarity of discussion I just describe outgoing journeys in this post as return journeys are exactly the same from a map point of view.

Tuesday, November 8, 2011

Google, Bing and OSM Maps: Zooming Symbolization

How Symbolisation changes with Zooming Out: A couple of weeks ago I sang the praises of Google’s 3D building symbolisation. I said putting 3D building models into Google maps with a faded gray coloring could really help people using their maps to navigate around a city. Such models represent symbolisation: the simplification of reality (3D buildings) into simpler symbols that help understanding. This week I look at how the symbolisation of buildings changes as user’s zoom out from a close in view.  I'm assuming that the user is doing some sort of navigation task again and I compare
  • Google maps
  • Bing maps
  • OpenStreetMap
Change Sucks: The first thing to point out is that evidence from my PhD student Craig’s work on the usability of maps shows that changing symbolisation as users zoom out makes it difficult for users to track what’s going on. So any sybmolisation change, say from a building polygon to a point symbol, has a mental  ‘cost’ to it, symbolisation should only change where there is good reason to do so.

Polygons to Points: So how should building symbolisation change as a user zooms out from an urban landscape? A good best practise is to have buildings represented as polygons at low altitude. As the user zooms out, the polygons become difficult to differentiate visually so it makes sense to change symbolisation to a labelled point. This is exemplified by Google’s rendering of the White house as in the screen video below. (apologies for the quality and varying sizes of the videos below, I'm experimenting with a new screen capture tool and haven't got it all worked out yet)

Points to note:
  • The symbolisation starts out as a 3D gray model
  • It switches to a polygon on zooming out
  • At all times the building is represented by a labelled point. As the user zooms out the polygon disappears and we are left with just the labelled point.
Its pretty faultless, every change in symbolisation is helping the user and it's an intuiative system.

Parliament by Google: So how does the white house example compare with the UK seat of government, the houses of parliament?

Oh dear, nowhere near as good.  A clear glitch that all labels and symbols disappear at altitude.

Parliament by Bing:  How does that compare to Parliament by Bing Maps?  Bing uses a different approach, instead of having one base map that switches symbolisation as you zoom out they have incorporated an old static style road map as the base level which changes at altitude to what amounts to a completely different map.

As you can see, the symbolisation at the lowest level is better than Google's Houses of Parliament but less good (IMHO) than Google's White House.  As you zoom out, the symbolisation stays the same which is easy to follow as a user, but the view becomes very cluttered.  The switch to a completely different map system is clumsy at best.

OpenStreetMap:  In comparison OpenStreetMap does well at low altitude with good labeling (shown here as an image rathe than a video):

Their approach is to have labels without points which then disappear at altitude while the polygons persist.  I think a labelled point at high altitude is the better system.  This alternative technique isn't too bad visually as the polygons are a neutral color and, as we've discussed,  keeping symbols the same helps users understand the map.  However, if the polygons became paled out at high altitude (so they blended in with the background) then they would work better IMHO.  This is because the road network operates as a landmark system at altitude so needs to become visually dominant over the buildings. 

Conclusion:  I wouldn't want to generalize to judging the quality of these three mapping systems on the 'Houses of Parliament' test.  As we've seen with Google, the quality can vary from place to place.  Its also easy to pick holes with mapping systems in this way, there's an enormous amount of work in producing intelligent symbolisation for multiple zoom levels across the entire globe and the visibility of polygons, labels and points at different zoom levels has to be automated in some way.  However, IMHO the symbolization could be improved in all of these three map systems and the building is important: its the seat of government in a G20 country and a major landmark in a world class city.    

Wednesday, November 2, 2011

Streetiview vs Streetside from a users point of view

So there has been a lot of blog posts on the internets comparing Bing's Streetside with Google's Streetview.  Mostly these cover technical and privacy points:

Streetview: Much larger coverage (certainly in the UK), Full 360 degree view

Streetside:  Avoided some of the privacy controversy by targetting 'super public' areas such as city centres rather than residential areas.  Viewing is more limited to a row view of buildings that slides by.

No one has covered the usability issues in detail so I thought I'd make some observations, to do this I need to go off on a bit of a tangent into 3D virtual environments:

Less Control = Easier to Use:  I've just finished a draft of a paper in which I reviewed Google Earth Tours.  One thing I discovered in the literature is that in 3D environments (Google Earth, Second Life) the 6 degrees of freedom* that a user needs to control can cause problems of usability:
  • Walls aren't solid: Users can crash through model walls which is disorienting
  • Desert Fog: Users end up very close to a plane surface like the ground, they can't see any features to orient themselves or guess scale - they are said to be experiencing desert fog.  
  • Peripheral Vision:  Because of the limited computer window into the environment they miss visual clues from their peripheral vision that they pick up in the real world (better in a CAVE setup or similar of course) 
Limiting their degrees of freedom of movement can help users avoid these issues.   An example is a tower in Second life - if a user can be 'locked' into moving around it so they can only fly a fixed distance from the tower and their vision is locked directly towards the tower they would avoid some of the problems listed above.  Their degrees of freedom have been reduced from 6 down to 2 (they can only fly up/down outside the tower, orbit it left/right) but they can still explore it.  Even more radical in a Google Earth tour users only have VCR play/pause/rewind controls effectively reducing their freedoms of movement down to 1.  

Streetside Constrained Freedom:  Streetside has taken the same 'constrained view' approach.  They allow a user to only look directly at the side of the road, this is sensible as in a cityscape as this is the most useful view.  To switch view to the other side of the street you simply click a little 180 degrees view button which zooms you around.  Streetside:
  • Mutiple Controls: Avoids problems of having to operate multiple controls (in Streetview they may expect double clicking to zoom them into a photo view, in fact it moves their position)
  • Look Sideways: Allows users to move along a street whilst looking at buildings.  In Streetview users have to face foreward to move foreward, to look at the buildings on the side of a road they need to stop and turn.
UPDATE 3rd Nov:  Actually that's not strictly true.   Streetside offers 'slippy slides' of the street going past which is better than Streetview's click-refresh operation.  However, you can arrange Streetview so you're looking side on to the street and then click the arrows so you move along.  Its quite clever actually.   
  • Fast: Allows users to whisk along a street in a zoomed out view faster than moving through Streetview (in a little informal test I did myself, see the zoomed out view that allows this in the above screenshot )
However, this comes at a cost.  Streetview has the advantages:
  • Less Disorientation: I think its easier to become disorientated by moving down a street only looking at one side.  Certainly for testing out a cycle route across a town, Streetview is more natural and would be the better tool.
  • Photo stitching is better in Streetiview, in Streetside I noticed whole streets warped out of view.  This may be a technology issue that is solved soon but at the moment it's a real issue.
  • 3D Buildings: While looking at Streetview, Google Maps also supplies 3D building models (earlier post on this topic see screenshot above) which further helps with orientation. 
I think the Streetside approach is very sensible and may well be better than Streetview in cities.  However, outside of urban areas you would need to use Streetview as the side of a road becomes far less interesting.  IMHO the best product would offer both these approaches.  

*Avatar: up/down, forwards/backwards, left/right
  Camera orientation: yaw, pitch, roll