Re: [OSGeo-Discuss] Proposal: OSGeo Cartographic Library
Markus Neteler kirjoitti: Dear OSGeo, I would like to launch the idea of an OSGeo Cartographic Library to share concepts, source code and regression tests: http://wiki.osgeo.org/wiki/OSGeo_Cartographic_Library I proposed a year ago to develop a geospatial graphics library based on Cairo http://www.intevation.de/pipermail/freegis-list/2007-April/003142.html I'm still very much interested in this. Cairo would provide a single API to render to an image buffer, on PDF and others. It has good support for rendering text with various fonts and there are high-level language APIs. Currently Cairo can be used in Geoinformatica to render geodata, legends, etc. on a map. I'm already using that a bit and will use it much more in the future. What I think is needed first, and would be the core content of the library is 1) a mapping of style information into Cairo commands, 2) capability to render cartographic symbols on maps, and 3) a mechanism to allow plugins that add legends etc. on the map, 4) symbol and label placement algorithms. Second need would perhaps be support for various geovisualization methods. 1) is rather straight-forward, I guess, using OGC Styled Layers standard 2) I'm not sure, there seems to be free resources like http://pubs.usgs.gov/of/1999/of99-430/ which offer symbols in EPS -- I don't find support in Cairo to render EPS on surfaces 3) is rather straight-forward 4) start from simple and existing codes Cairo is of course just one technology and not suited for all needs in this domain. Furthermore, the data provider can be made separate from the library, but I'd like to start with and use GDAL (OGR in fact) as the default. Anyway, I'd like to finally get going with this and start drafting an API. Any ideas how to proceed? Set up a svn repository somewhere? Regards, Ari -- Prof. Ari Jolma Geoinformatiikka / Geoinformatics Teknillinen Korkeakoulu / Helsinki University of Technology tel: +358 9 451 3886 address: POBox 1200, 02015 TKK, Finland Email: ari.jolma at tkk.fi URL: http://www.tkk.fi/~jolma ___ Discuss mailing list Discuss@lists.osgeo.org http://lists.osgeo.org/mailman/listinfo/discuss
Re: FW: [OSGeo-Discuss] Proposal: OSGeo Cartographic Library
Hi, this mail was forwarded to me, and I immediately subscribed to the mailing list to set something straight. Rushforth, Peter wrote: In the XML world, the answer to graphics rendering is SVG + XSL-FO, generated by XSLT scripts according to styling rules. XSL-FO is then rendered via a formatting objects processor, like Apache FOP. OK, but... you do know that this is only true for small datasets. For large datasets FOP is a bad choice performance wise. For instance: if you have to convert an XML to a PDF and you expect the end result to be 50 pages, Apache FOP might be a good choice. If you expect 10,000+ pages, then it's a bad choice. A document with 10,000+ pages is not as unusual as most PDF newbies think. I've just created a PDF with 28,500 pages; each page is a letter to one of the 28,500 students of Ghent University. I've heard from banks that create PDFs with 100,000+ pages. In this case, I use iText (obviously: I'm the developer of iText): http://www.lowagie.com/iText/ iText is used by Google, NASA, DoD,... It's purpose is to create all kinds of PDF files as fast as possible. I'm of the opinion that a pipeline like: GML +/- (any XML data) + SLD/FE + WMS graphics = XSLT = SVG+XSL-FO - pdf, (?geopdf anyone?) XSLT? XSL-FO? What a performance killer! would make for a killer map scripting environment. Plus, it has the added benefit of being based on standards or de facto standards across the board, with open source solutions available in each area. Use Cases: -- I. Interactive Browsing (e.g. web mapping) 1. Good-looking web maps (more control of grid/graticule labeling) FOP doesn't support all PDF features. For instance: I've made a map in PDF that shows a raster image when you first open it. Then when you zoom in, the PDF automatically switches to vector data. FOP doesn't support OCG! iText does! OCG = Optional Content Groups: meaning you can turn on and off layers in a PDF file. For instance: you could add street names to a map in English en French and define the OCG so that only one language at a time is shown. II. Ad-hoc Authoring (one-time GIS style layout using GUI) 1. Good-looking printed (ps,pdf,etc) maps automatically providing grid/grat, scalebar, legend, north arrow, SRS description - provide an API to exiting GIS apps? FOP isn't fast enough to create detailed PDFs on the fly. III. Automated Mapping (script driven) 1. Map Series (single page, identical layout) 2. Map Atlas (mostly map with some text, multi-page) 3. Map-centric documents (mostly text with some map, multi-page) 4. Route Alignment Sheets (rotated (non 90 deg) to fit page) With iText you have direct access to all PDF operators and operands. you can draw every shape you want. Please download chapter 1 of my book: http://1t3xt.com/docs/book.php#free There's an example of a map of a (fictive) city. I hope you'll find it very interesting! br, Bruno ___ Discuss mailing list Discuss@lists.osgeo.org http://lists.osgeo.org/mailman/listinfo/discuss
Re: [OSGeo-Discuss] Proposal: OSGeo Cartographic Library
On Sun, Apr 13, 2008 at 11:18:48AM +0300, Ari Jolma wrote: I'm still very much interested in this. Cairo would provide a single API to render to an image buffer, on PDF and others. It has good support for rendering text with various fonts and there are high-level language APIs. Currently Cairo can be used in Geoinformatica to render geodata, legends, etc. on a map. I'm already using that a bit and will use it much more in the future. I think that for the task you've described, looking into Mapnik might be a good idea. What I think is needed first, and would be the core content of the library is 1) a mapping of style information into Cairo commands, 2) capability to render cartographic symbols on maps, and 3) a mechanism to allow plugins that add legends etc. on the map, 4) symbol and label placement algorithms. Second need would perhaps be support for various geovisualization methods. 1), 2), and 4) already exist in Mapnik. 3) seems to me like it can either be added to Mapnik, or added via post-processing, without needing to reimplement 1), 2) or 4). Cairo is of course just one technology and not suited for all needs in this domain. Furthermore, the data provider can be made separate from the library, but I'd like to start with and use GDAL (OGR in fact) as the default. Mapnik has support for PostGIS and Shapefiles, but has a plugin-based architecture for reading data, so I would not be surprised to find that an OGR plugin for data access would be too difficult for someone experienced in C++/C. Anyway, I'd like to finally get going with this and start drafting an API. Any ideas how to proceed? Set up a svn repository somewhere? I'd strongly recommend starting by looking at existing solutions. Regards, -- Christopher Schmidt Web Developer ___ Discuss mailing list Discuss@lists.osgeo.org http://lists.osgeo.org/mailman/listinfo/discuss
Re: [OSGeo-Discuss] Proposal: OSGeo Cartographic Library
On Sun, Apr 13, 2008 at 2:58 PM, Christopher Schmidt [EMAIL PROTECTED] wrote: On Sun, Apr 13, 2008 at 11:18:48AM +0300, Ari Jolma wrote: I'm still very much interested in this. Cairo would provide a single API to render to an image buffer, on PDF and others. It has good support for rendering text with various fonts and there are high-level language APIs. Currently Cairo can be used in Geoinformatica to render geodata, legends, etc. on a map. I'm already using that a bit and will use it much more in the future. I think that for the task you've described, looking into Mapnik might be a good idea. Some more is here: http://grass.osgeo.org/grass63/manuals/html63_user/cairodriver.html Markus ___ Discuss mailing list Discuss@lists.osgeo.org http://lists.osgeo.org/mailman/listinfo/discuss
Re: [OSGeo-Discuss] Proposal: OSGeo Cartographic Library
Ari Jolma wrote: Markus Neteler kirjoitti: Dear OSGeo, I would like to launch the idea of an OSGeo Cartographic Library 3) a mechanism to allow plugins that add legends etc. on the map 3) is rather straight-forward Actually, dealing with the legend, or the contents of the entire map collar, is non-trivial, however, a library that can render the content within a map's neat line has all the tools necessary to be able to render the map's collar. The difference may be that there would need to be some additional functionality, or different methods of calling the same underlying functionality, in order to make the tasks involved in composing the collar easy. -- Dave Patton CIS Canadian Information Systems Victoria, B.C. Degree Confluence Project: Canadian Coordinator Technical Coordinator http://www.confluence.org/ OSGeo FOSS4G2007 conference: Workshop Committee Chair Conference Committee member http://www.foss4g2007.org/ Personal website: Maps, GPS, etc. http://members.shaw.ca/davepatton/ ___ Discuss mailing list Discuss@lists.osgeo.org http://lists.osgeo.org/mailman/listinfo/discuss
Re: [OSGeo-Discuss] Proposal: OSGeo Cartographic Library
Dave Patton wrote: Actually, dealing with the legend, or the contents of the entire map collar, is non-trivial, however, a library that can render the content within a map's neat line has all the tools necessary to be able to render the map's collar. The difference may be that there would need to be some additional functionality, or different methods of calling the same underlying functionality, in order to make the tasks involved in composing the collar easy. If you make the map in PDF, you could provide the legend as a floating annotation that can be moved around by the user. If you are using OCG, you also have the Optional Content panel that can be used as a legend and that can be used to make certain layers visible/invisible. All this is fairly easy to achieve in PDF. br, Bruno ___ Discuss mailing list Discuss@lists.osgeo.org http://lists.osgeo.org/mailman/listinfo/discuss
Re: [OSGeo-Discuss] Proposal: OSGeo Cartographic Library
On 13-Apr-08, at 9:23 AM, Bruno Lowagie wrote: If you make the map in PDF, you could provide the legend as a floating annotation that can be moved around by the user. If you are using OCG, you also have the Optional Content panel that can be used as a legend and that can be used to make certain layers visible/invisible. For me the question of PDF is not limited by number of pages, or options that PDF offers, but whether or not it is an efficient format for sharing cartographic information - for which, so far, I'd say it fails miserably. How many times have I went to a municipal mapping site only to find their maps are all in PDF - what a pain! It might just be me though :) Also, in the operational/industrial GIS map production environments I've been in, we've needed easy ways to print and re-print maps without having to open a viewer (and our printers didn't support PDF natively - though I assume some do now). To print, I've focused on native plotter file formats and/or Postscript since most plotters can support it. Of course this isn't going to be good for web distribution. For delivering digital files, I've often converted the PS files into PDF but it's been far from ideal. I increasingly believe that web- based tools are going to be the only option. So what about off-line delivery? A CD or USB runable system is an interesting and more effective way than a PDF in some cases, though of course both have some memory overhead issues. So, is it just me or does stuffing a 1:20,000 topo map into a PDF makes a huge file that is virtually unusable unless you have gigabytes of RAM and dual processors. Delivering a 40MB PDF to client who is running an old computer doesn't bode well for your service ;-) For what it's worth, Tyler ___ Discuss mailing list Discuss@lists.osgeo.org http://lists.osgeo.org/mailman/listinfo/discuss
Re: [OSGeo-Discuss] Proposal: OSGeo Cartographic Library
Tyler Mitchell (OSGeo) wrote: For me the question of PDF is not limited by number of pages, or options that PDF offers, but whether or not it is an efficient format for sharing cartographic information - for which, so far, I'd say it fails miserably. How many times have I went to a municipal mapping site only to find their maps are all in PDF - what a pain! It might just be me though :) It depends on how they are made. Do they have a street index that allows you to jump to the exact location when you click on a streetname? Are they made out of raster images converted to PDF or are they drawn using vector data? Also, in the operational/industrial GIS map production environments I've been in, we've needed easy ways to print and re-print maps without having to open a viewer (and our printers didn't support PDF natively - though I assume some do now). To print, I've focused on native plotter file formats and/or Postscript since most plotters can support it. Of course this isn't going to be good for web distribution. There are ways to work around that print problem ;-) For delivering digital files, I've often converted the PS files into PDF but it's been far from ideal. But then you get a 'flat' PDF without any interactivity. I don't see any added value when you convert PS to PDF. I increasingly believe that web-based tools are going to be the only option. So what about off-line delivery? A CD or USB runable system is an interesting and more effective way than a PDF in some cases, though of course both have some memory overhead issues. So, is it just me or does stuffing a 1:20,000 topo map into a PDF makes a huge file that is virtually unusable unless you have gigabytes of RAM and dual processors. Delivering a 40MB PDF to client who is running an old computer doesn't bode well for your service ;-) Er... stuffing a 1:20,000 topo map. The fact that you mention 1:20,000 indicates that you are probably talking about raster images, not about vector data. If you write the vector data to a PDF, all the data is compressed. You get really small file sizes when compared to other solutions. In short: the major problem with PDF in the GIS world is a lack of understanding of the Portable Document Format by people who are specialized in GIS. Of course PDF sucks if you just stuff if with raster images or use a PDF that was converted from PS. Even a FOP generated PDF has no added value. As soon as I have the time, I'll make you some examples. br, Bruno ___ Discuss mailing list Discuss@lists.osgeo.org http://lists.osgeo.org/mailman/listinfo/discuss
Re: [OSGeo-Discuss] Proposal: OSGeo Cartographic Library
www.openstreetmap.org j Bruno Lowagie píše v Po 14. 04. 2008 v 07:26 +0200: Bruno Lowagie wrote: As soon as I have the time, I'll make you some examples. My main problem is that I haven't been on a GIS project since 1997. Can somebody provide me with some (completely free!) sample data: - vector data with streets and street names in multiple languages - vector data of some shapes (for instance a city, municipalities) - some additional data, for instance: location of hotels, landmarks,... If you provide me with such a data set, I'll make you a PDF and show why I think PDF is an ideal format. br, Bruno ___ Discuss mailing list Discuss@lists.osgeo.org http://lists.osgeo.org/mailman/listinfo/discuss -- Jachym Cepicky e-mail: jachym.cepicky gmail com URL: http://les-ejk.cz GPG: http://www.les-ejk.cz/pgp/jachym_cepicky-gpg.pub signature.asc Description: Toto je digitálně podepsaná část zprávy ___ Discuss mailing list Discuss@lists.osgeo.org http://lists.osgeo.org/mailman/listinfo/discuss
