[OSM-talk] Is *just* tracing useful?

[David Groom]

> ----- Original Message ----- 
> From: "Tom Chance" <tom at acrewoods.net>
> To: <talk at openstreetmap.org>
> Sent: Friday, September 07, 2007 12:26 AM
> Subject: Re: [OSM-talk] Is *just* tracing useful?
>
>
> On Friday 07 September 2007 00:08:30 Dave Stubbs wrote:
>> Now my question is this: is this tracing actually useful?
>>
>> From my mapping perspective:
>> - it makes it much harder to see what needs doing
>> - when loaded onto my GPS the traced stuff becomes very difficult to
>> distinguish, so it takes me longer and I also miss stuff because I assume
>> it's been done.
>> - entering the data takes longer because I have to fix all the oneway
>> streets, and the ways that don't follow the roads, the ways that aren't
>> roads, and all the bits that were missed anyway... it's much quicker to
>> generate from scratch correctly
>>
>> In other words, I'd rather people didn't do it!
>
> I concur, in the area I've been mapping I usually end up spending more 
> time
> deleting old segments and waysthan I do putting mine in from scratch. 
> Unless
> you've been there you just don't know what the roads are like.
>

I disagree entirely.

1) there are areas of the world in which we will find it very hard to get 
complete coverage unless we use Yahoo imagery.  Ok, so we may at this stage 
only have the road layout and not the names, but it's better than nothing. 
Furthermore I've mapped large areas using Yahoo imagery, and then found 
other users have gone back and annotated the roads with names etc.  These 
people did not draw the road in the first place, and so the areas would 
still be blank

2) Say I've mapped an area, using GPS, add it to OSM, then look at Yahoo 
imagery and note I've missed off a few roads. Are you really suggesting I 
don't add them in just because I don't have a GPS trace for them?  I thought 
we were aiming for a complete map.

Toms comment about deleting old segments and ways is equally applicable to 
ways and segmnets added using GPS traces, where the person adding them has 
been less than meticulous in (a) tracing accurately over a GPS track, (b) 
actually making segments into ways (c) annotating those ways correctly. The 
complaint relates to inaccurate mapping skills by the user, and not the 
tools the user is using.

With careful use of the Yahoo imagery it is possible to make a very educated 
guess about what it is you are mapping. In my experience the majority of 
mapping time is taken by defining the route of a road / path, and whether 
this is done by tracing a GPS track, or tracing from Yahoo is irrelevant. 
Particularly with the tools in JOSM it is easy to split or combine ways, so 
if the initial mapping via Yahoo is not accurate then things can be easily 
corrected.

David

> I'm sure some people do it with the intention of then visiting the area, 
> so it
> can't all be bad. But where I've been working it looks like people have 
> just
> randomly added odd bits of roads, parks, etc.

So there are random parks, so what?  Surely its better than a whole load of 
white space on the map?  I'll hold my hand up here and admit I've added 
loads of woodland from the Yahoo imagery, I'm never going to walk around the 
boundary of those woods, same with the parks, beaches, and the coastline 
I've corrected using Yahoo imagery.

Complain about inaccurate mapping if you like, but don't single out one 
particular method for complaint!

David
>
> Kind regards,
> Tom