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Archived  - Use Search => Archived - Feedback and Comments => Topic started by: alizhan on April 23, 2005, 10:46:59 PM

Title: Zoom and Tileset Suggestions
Post by: alizhan on April 23, 2005, 10:46:59 PM

I have a few suggestions regarding the handling of tileset and zoom factor in the TF interface. Since these suggestions may not make sense on their own, I'll start by describing the situations which prompted them.

First, there are times when I wish I could manually control which tileset is being displayed, independent of the current zoom level. For example, my preferences are set so that a zoom of 8.88 maps to Topo 16M, but for this particular map I'd rather use Topo 4M. You can sometimes force TF to do this by messing with the preferences, but not always.

Second, I often wish I had a way to switch to an exact zoom level. Relative zoom is nice, but I find myself wanting to reset the zoom to a specific value every so often (most commonly, 1.0). The tileset selector provides a partial solution, but only if you are changing tilesets. If I'm using Aerial 4M, and want to jump to 1.0 zoom, I can simply select Aerial 1M. The tileset is changed, and the zoom set to 1.0. But there's no easy way to set the zoom to 4.0 when using Aerial 4M; selecting Aerial 4M does nothing as that is already the current tileset. Instead, I have to change tilesets twice: away from Aerial 4M, and then back again. This is frustrating, especially on an old computer like mine, which is painfully slow at scrolling scaled maps.

Finally, a related problem shows up when editing tracks. I'm examining the map, and see something which bears closer inspection. I zoom way in, and disentangle some trackpoints. But when I'm done, there's no easy way to get back to the view I just left.

The first two of these are easy to fix--at least from a user interface perspective. One normally wants the tileset to be linked to the zoom level, but not always. One could add a checkbox between the zoom level and tileset droplist which controls this linkage. When checked, TF acts as it does now; when cleared, zoom and tileset act independently. To easily control the precise zoom factor, one could make the zoom display control a combobox; the droplist would contain common zooms (0.25, 0.5, 1, 2, 4, 8, etc.), and the user could type in an exact zoom level.

The last item is slightly harder: it implies a history of views, with the ability to move back and forth between them. The metaphor used by web browsers may be of use here. One has the current, live view, and a history of saved views. Buttons allow one to move back and forward through this list, and to push a new saved view. Moving or zooming makes the current view the live view, and discards any "forward" views from there. One could even get fancy and allow combinations like holding the SHIFT key while zooming with the magnifying glass to automatically save the view before zooming.

I know this was a pretty long post, but I think these minor interface changes would improve the ergonomics of the interface greatly.

Title: Zoom and Tileset Suggestions
Post by: Alan on April 24, 2005, 03:41:52 PM

First, note that the "Tile Sets" tab in the options dialog allows you to turn off tilesets, so you only get the ones you want.

In general it is not a good idea to unlink the zoom and tileset.  Consider what happens if one is zoomed out far enough to see an entire state.  What happens if the user wants to see Aerial 1M at this level?  Each tile is smaller than one pixel at this view.

For limited uses, it's a good idea, but that's why we provided the list of checkboxes in the options dialog.

I'm not sure about the history of views.  Do you know of any other mapping program that provides this functionality.  I don't think your web browser saved the state of the scrolllbars such that you can press back/forward to move back and forth through different "view" of the page.  It's an interesting idea.  Right now, the only way to really save your place is to create a GPX file with a waypoint or something there.

Title: Zoom and Tileset Suggestions
Post by: alizhan on April 26, 2005, 07:10:26 PM

Quote (Alan @ April 24 2005,4:41)

First, note that the "Tile Sets" tab in the options dialog allows you to turn off tilesets, so you only get the ones you want. [...] For limited uses, it's a good idea, but that's why we provided the list of checkboxes in the options dialog.

True, but it's a hassle to keep changing those settings. What I was suggesting was basically a way to do this more efficiently. The Preferences dialog records what the default behavior should be, while this new functionality controls specific exceptional cases (e.g., "TF wants to use Aerial 4M for this, but I'd like to see it using Aerial 1M").

Quote (Alan @ April 24 2005,4:41)

In general it is not a good idea to unlink the zoom and tileset.  Consider what happens if one is zoomed out far enough to see an entire state.  What happens if the user wants to see Aerial 1M at this level?  Each tile is smaller than one pixel at this view.

But TF won't allow that anyway: it stops drawing tiles when the scaling gets too far out of whack (under the control of that Preferences slider). So I guess I don't see the harm in allowing it. If the user chooses a bad combination, they get a bad map. I don't see novice users using this capability, anyway.

Quote (Alan @ April 24 2005,4:41)

I'm not sure about the history of views.  Do you know of any other mapping program that provides this functionality.  I don't think your web browser saved the state of the scrolllbars such that you can press back/forward to move back and forth through different "view" of the page.  It's an interesting idea.  Right now, the only way to really save your place is to create a GPX file with a waypoint or something there.

That idea is straight from my fevered brain. Mozilla and Internet Explorer both try to save the scrollbar state when following links (but, obviously, not when just scrolling around), though they both often get it slightly wrong due to HTML rendering issues. In this case, TF has an advantage, as the exact center, zoom, and tileset are known.

I'd be happy to work up a step-by-step if an example would help illustrate the idea.