Ranting about Potlach

Posted by egore911 on 4 September 2008 in English (English).

Several times I saw changes when suddenly a "created_by"="Potlach" appeared. Many of these changes were wrong and I often accused Potlach of being the one to blame. But I was wrong: The default audience of Potlach is to blame. Don't get me wrong: I don't say everyone who uses Potlach will only make mistakes! But some things should really not happen. Let's take an example:

I got the city boundaries for Koblenz from an official department. I added them 2 days ago and today I found out that someone moved one of them. It does not make any sense. I doubt it was done intentional. But it happend.

Also many things are done based on yahoo images (or however this is called). This is great for forests, railways and straigt wide streets ... but not for complicated crossings. Take a look at:
This is the most complex crossing/link I know of. And someone worked on it based on the images ... using Potlach ... completely wrong. I avoided doing it (until few days ago) using JOSM for a while since I know this place very well and it is just to complicated. By the way (at least I think so) the user several dozen of kilometers of the street of being a bridge ... which was wrong, too.

So I wonder if there is anything we can do to help Potlach users. I can think of 3 things that really help me in JOSM:
* The validator plugin. It fetches a lot of mess I create before I upload it.
* Bridges recently got a "blue overlay" in JOSM. This really helped me to see where I did bridges and helped me rethink a few of it.
* Explicit saving. In JOSM you need to upload your changes by clicking a button. I really like to see a "Save" button in Potlach so an average user can do as much as he/she likes without actually destroying things.

If I got anything incorrect feel free to correct me. This is just my (currently a it frustrated) point of view.

Thanks for reading :-D

Comment from CoreyBurger on 4 September 2008 at 02:19

Don't blame the tool or the users who are using it. Remember,those are the mappers today who will become great mappers in the future. It is better to fix the issues with the tool AND help with new-user education.

Comment from iridium on 4 September 2008 at 07:34

I think it should be possible to tag map features with different levels of certainty. Then, the software should ask the user to confirm before changing something that is already marked with high enough degree of certainty.

Comment from ndim on 4 September 2008 at 08:00

The automatic saving in Potlach works nicely in my usual workflow -- however, it *is* lacking a multistage undo/redo function and perhaps a list which explains the changes between these stages as text.

This makes it about impossible to completely undo any mistake I have made -- I must resort to remembering what it was before and then reconstructing that state, which is very much prone to errors.

Comment from Richard on 4 September 2008 at 10:27

ndim: There is an undo (though not redo) function, but I'm aware it's not perfect. If you identify any bugs in it please do report them via trac - it'd help enormously.

egore911: First of all, I do appreciate that you make a distinction between "Potlatch" and "newbies", too many people don't.

For the three specific points, different rendering for bridges will be addressed in an upcoming version - probably the next few weeks. The vaildator plugin per se is not appropriate for the Potlatch audience, but there's clearly a need for a more interactive display of "what you're doing, and how it could be improved" to accompany editing, and that's planned for the medium term.

On the 'Save' button, I've said several times that I'm not against it per se. In fact, I think it would be quite helpful to expand the practice mode of Potlatch to have a Save button. That way you'd have the choice of editing live (as at present) or session-based editing with Save.

The problem is, though, that I really don't have the time to do this. A Save button will require a lot of thought and coding, because you have to implement conflict resolution (i.e. what happens if someone else has been editing the ways in the intervening period). The UI for that needs to be good - and by way of illustration, last time I looked (though this was a long time ago), JOSM's conflict UI wasn't intuitive enough for the Potlatch audience.

However, right now I also have on the 'to do' list: fixing the long-standing issue with duplicate nodes when the server's slow (which will be a lot of work); a new tagging UI; a new interactive help system (which ties in with your point about the validator plugin); and about eight zillion trac tickets (take a look). There's another big expansion I've been asked to do this autumn which'll take several weeks' coding. Oh yes, and Steve wants me to recode the whole lot in ActionScript 3.

I can't do that all on my own. I'd be hard-pushed to do so if Potlatch was my paid job - which clearly it isn't, it's just one of several hobbies.

So if you want a Save button, either you're going to have to code it, or you'll have to find someone else who can. Potlatch is all public domain; it compiles with a free compiler; ActionScript 1 is exactly the same language as JavaScript but with a different API; and I'm very happy to help by explaining how it all works. It's not really difficult. But, I'm afraid, it's not going to happen unless someone steps up and helps.

Comment from POHB on 4 September 2008 at 11:27

I've tried JOSM and found it much less intuitive and slower to use than Potlach, and I'm a software developer of 25 years standing. Also I tend to make most of my edits in spare time while at work and only have access to OSM via a browser through a firewall.

I'd suggest that the issue isn't so much with the editors but with the back-end systems. All the history is stored in the database so if we could easily compare before/after views and revert changes that stuffed things up it would be great. Also, if the tiles were re-rendered more quickly then folks could see the effects of their changes as soon as they made them and it'd be more obvious if things were bad. A "what's new" view would be good too.

The time must surely come soon when someone starts making malicious edits, either subtly or just deleting swathes of stuff. This will be painful unless reverting changes is made easy.

Yes, I know that all this is being thought about already and requires someone's unpaid time to implement so I'm not really being helpful here :-(

Comment from HannesHH on 4 September 2008 at 16:09

The "problem" with Potlatch is that is (apparently) so easy to use. That is a bad thing as people can much easier screw up, BUT the benefit of it surely weighs in for that. The "fix" would probably be better guides and help for newbies generally.

Comment from TEL0000 on 5 September 2008 at 01:28

For the crossing there are no good yahoo-images. So i don't think, that anyone worked on it, based on the images...

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