229 |
to go back, without a "back button" [implies bidirectional links] |
to go back, without a "back button" [implies bidirectional links] |
230 |
"once you get there, you should see how you can get back". |
"once you get there, you should see how you can get back". |
231 |
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|
232 |
|
There is one scrollable focus node ("current document"), |
233 |
|
and links |
234 |
|
|
235 |
To be able to show all the link targets near the focus, |
To be able to show all the link targets near the focus, |
236 |
only the *relevant fragments* (the immediate surroundings of the other |
only the *relevant fragments* (the immediate surroundings of the other |
237 |
end of the link) of the target nodes can be shown. |
end of the link) of the target nodes can be shown. |
294 |
- the view should animate continuously when the focus moves |
- the view should animate continuously when the focus moves |
295 |
- the user should be able to understand and predict the motion |
- the user should be able to understand and predict the motion |
296 |
of the buoys. |
of the buoys. |
297 |
|
- there should be little or no hysteresis |
298 |
- buoys should be placed close to their anchors |
- buoys should be placed close to their anchors |
299 |
|
- time coherence: when traversing a link, i.e. animating a buoy into focus, |
300 |
|
the former focused node should have a clear relationship. |
301 |
|
|
302 |
Furthermore, |
The apparent conflict between "no hysteresis" and "time coherence" |
303 |
it is important to maintain orientation locally, |
can be resolved by maintaining a local spatial structure |
304 |
that is, going in one direction should result in arriving from |
by giving each link a specific left-right orientation |
305 |
the opposite direction, so that the local spatial structure |
so that a right-end node and left-end node retain their relative |
306 |
does not change too much. |
locations w.r.t. to the link |
307 |
|
independent of either of them being the main node. |
308 |
This matches the way the brain understands space |
This matches the way the brain understands space |
309 |
as globally distorted, segmented, locally Euclidian views |
as globally distorted, segmented, locally Euclidian views |
310 |
(see, e.g. [wang01mindsviews]_). |
(see, e.g. [wang01mindsviews]_). |
311 |
|
|
312 |
|
.. it is important to maintain orientation locally, |
313 |
|
that is, going in one direction should result in arriving from |
314 |
|
the opposite direction, so that the local spatial structure |
315 |
|
does not change too much. |
316 |
|
|
317 |
.. http://acad88.sahs.uth.tmc.edu/research/publications/iccs2001spatial.pdf |
.. http://acad88.sahs.uth.tmc.edu/research/publications/iccs2001spatial.pdf |
318 |
.. http://citeseer.nj.nec.com/hunt99orientation.html |
.. http://citeseer.nj.nec.com/hunt99orientation.html |
319 |
|
|
|
Because of this, each link has a specific left-right orientation |
|
|
so that a right-end buoy is drawn on the right side of the view |
|
|
and a left-end buoy on the left side. |
|
|
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|
320 |
More than two opposing directions could also be used, but |
More than two opposing directions could also be used, but |
321 |
is is not required for the local spatial coherence and it would also |
is is not required for the local spatial coherence and it would also |
322 |
limit the layout of a large number of buoys. |
limit the layout of a large number of buoys. |
323 |
Furthermore, there is usually no meaningful global 2D layout for |
Furthermore, there is usually no meaningful global 2D layout for |
324 |
a network of nodes, so the extra directions would not help much |
a network of nodes, so the extra directions would not help much |
325 |
in perceiving the position in the global structure. |
in perceiving the position in the global structure. |
|
In our application, the structure has simply directed links, |
|
|
visualized as the left-right direction of the connection lines. |
|
326 |
|
|
327 |
As for the horizontal orientation of the link direction, |
Orienting the link direction horizontally |
328 |
it is more natural than vertial, |
rather than vertically is more natural |
329 |
because the visual field is wider than it is tall |
because the visual field is wider than it is tall --- |
330 |
(as exemplified by the usual screen aspect ratios of 4:3 and 16:9) |
consider the usual screen aspect ratios of 4:3 and 16:9. |
331 |
leaving more space at the left and right sides than on the top and bottom. |
|
332 |
XXX: left and right hand??? |
.. leaving more space at the left and right sides than on the top and bottom. |
333 |
|
XXX: left and right hand??? |
334 |
|
|
335 |
From the above principles, we have chosen a simple geometry |
From the above principles, we have chosen a simple geometry |
336 |
depicted in Fig. [ref-figbuoygeom]_. |
depicted in Fig. [ref-figbuoygeom]_. |