[Talk-br] Progresso com os mapas do IBGE

[Thiago Marcos P. Santos]

On 09-03-2014 22:43, Alex Barth wrote:
> Thiago -
>
> This tracing layer looks great.
>
> 2014-03-07 16:02 GMT-05:00 Thiago Marcos P. Santos 
> <tmpsantos em gmail.com <mailto:tmpsantos em gmail.com>>:
>
>     (um sonho que vai requerer muito poder de processamento e
>     espaço de armazenamento). :)
>
>
> Take a look at TM2. With TM2 you can render vector tiles (much smaller 
> than raster tiles) and then separately render the vector tiles on the 
> fly. You don't need to set up your own tile server but you can use 
> Mapbox, happy to provide an account for free for this project. Let me 
> know if you're interested or if you need help getting started on TM2.
>

Hi Alex,

I will definitely have a look at TM2 and thanks a lot for the free 
storage offer.

Now a few words on some technical challenges I'm having and maybe you 
can point if TM2 is adequate for the task and where I can plug TM2 on my 
rendering pipeline.

The main idea here is to convert scattered maps fragments made available 
by IBGE as PDFs into map tiles that can be used as support reference for 
urban map tracing.

PDFs are supposedly a vector format, but you can embedded byte streams 
objects into it. And that is exactly what IBGE did: there is not a 
single vector data on these PDFs. What the tool I'm developing does is 
extract the byte stream, which turns out to be a PPM image, crop the map 
from it and run a OCR to extract the coordinates. From that I generate 
GeoTIFFs for each PDF of a particular location. IBGE packs them by 
municipalities.

The next step in my pipeline is to take all the GeoTIFFs and merge into 
a single one. This is needed because they are in a different geographic 
scale, resolution and there are a lot of overlaps.

Finally, I'm generating raster tiles from this big GeoTIFF in different 
zoom levels. This is where I believe Mapbox can do its magic. :)

If I got the idea right, the fact that my map source is a raster image 
is a problem for TM2. I could maybe try to vectorize it, but I'm 
skeptical about the results (but I will have a look at things like 
libautotrace anyway).

Cheers,
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