OpenGuides-Dev

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701 discussions

[OpenGuides-Dev] Defacing resilience
by Dominic Hargreaves 30 Jun '04

30 Jun '04

A week or so ago someone completely destroyed the home page of the Oxford Guide [1]. This was a pain, and to recover the state I had to paste the content from mysql command line output because it wasn't possible to recover the earlier version from the CGI. Two possible solutions (ideally both should be implemented I think): - Implement a "delete revision" function (to go with the "Delete node" functions. I would not want to keep most malicious edits: bear in mind that you are still effectively publishing them through the historical versions. When this is spamming for googlejuice... [2] - Allow editing of historical versions: 16:40 <@grault> load the text of an earlier version into the edit buffer; save it as a new version when you hit save. Dominic. [1] http://www.ox.compsoc.net/oxfordguide/?id=Home&version=81 [2] http://www.ox.compsoc.net/oxfordguide/?id=Home&version=XX (replace XX with 65)

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RE: [OpenGuides-Dev] locator plugins
by IvorW 29 Jun '04

29 Jun '04

> -----Original Message----- > From: openguides-dev-bounces(a)openguides.org > [mailto:openguides-dev-bounces@openguides.org]On Behalf Of David > Cantrell > Sent: 29 June 2004 01:16 > To: OpenGuides software developers > Subject: Re: [OpenGuides-Dev] locator plugins > > > IvorW wrote: > > > An ellipsoidal projection about one great circle will only > provide an accurate projection > > regarding distances, for a very small percentage of > locations on Earth. > > I know we've talked about simply calculating distances from > point A to > point B on the surface of a sphere in the past, and rejected > it because > you lose accuracy over small distances, due to rounding > errors in cos() > and sin(). > > I wonder, if we used an arbitrary precision FP library like > Math::BigFloat does this problem go away? It doesn't provide trig > functions, but they can be derived thus: > > cos(x) = 1 - x^2/2! + x^4/4! - x^6/6! + ... (x in radians) > > and > > sin(x) = x - x^3/3! + x^5/5! - x^7/7! + ... > > This is guaranteed to give us accurate results provided we use > sufficiently accurate values for sin(x) and cos(x), I wonder > what the > performance hit would be. > More to the point is the accuracy of the other factor - the radius of the Earth. If you assume that this is a constant, you are assuming that the Earth is a sphere. Also, how would you go about measuring the distance from a given point on the Earth's crust to the centre of the earth? An alternative approach woud be to use a linear approximation (slides 24-26) http://un.earth.li/~ivorw/slides/geogmod.ppt Having defined an origin for our guide (e.g. Charing+, Carfax, etc.) We could go out there with a GPS and a trundle wheel (or some other means of measuring distances in a straight line accurately), and come up with the appropriate X and Y scale factors for our own grid. This was my original idea, before I learned about UTM and ellipsoids. Ivor.

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Re: [OpenGuides-Dev] locator plugins
by Jo Walsh 29 Jun '04

29 Jun '04

On Mon, Jun 28, 2004 at 06:48:23AM -0400, IvorW wrote: > I thought that you needed different ellipsoids for different parts of the globe. > wgs84 or nad83 may work well for California, but I doubt if they would for Europe. no, wgs84 is a global model. streetmap.co.uk gives you lat and long back in wgs84. you need to worry about the different archaic reference datums used in different countries grid projections only when projecting geodata onto flat maps that are already georeferenced according to the other projection. UTM is where this makes a difference for different countries grid systems - i wouldn't know my own local mapping agency projection, though... i would send a link with better metainfo but have to run... zx

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Re: [OpenGuides-Dev] locator plugins
by Kate L Pugh 28 Jun '04

28 Jun '04

On Sun 27 Jun 2004, Jo Walsh <jo(a)frot.org> wrote: > then i think the 2 plugins should be totally compatible, and i just > change mine to use base CGI::Wiki::Plugin::Locator::UTM, and add the > geocoding method. nice one ivor. Couldn't the two plugins be merged into one? And CGI::Wiki::Plugin::Locator::UK should be made obsolete as well. > a further thought! Schuyler objects that distances in metres and > kilometres meant little to people not used to seeing them / > converting between them and yards/miles, e.g. pesky merkins. On Mon 28 Jun 2004, IvorW <ivorw-openguides(a)xemaps.com> wrote: > Sounds like a case for using Data::Dimensions. That's real overkill for a simple conversion. Anyhow, it looks like you two have this well in hand so I shall leave it up to you. Kake

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Re: [OpenGuides-Dev] locator plugins
by Stephen Stewart 28 Jun '04

28 Jun '04

On Mon, Jun 28, 2004 at 06:48:23AM -0400, IvorW wrote: > > > > -----Original Message----- > > From: openguides-dev-bounces(a)openguides.org > > [mailto:openguides-dev-bounces@openguides.org]On Behalf Of Jo Walsh > > Sent: 28 June 2004 00:42 > > To: OpenGuides software developers > > Subject: [OpenGuides-Dev] locator plugins > > > > > > > an additional piece of data by way of the ellipsoid. This > > > needs to be prompted > > > for in the setup, and held in the config file. > > > > i kind of assume it will always be wgs84 - 23 for > > Geo::Coordinates::UTM - or nad83 which is centimetres of > > difference. this is what gps, the big mapping sites, etc use > > - this could be a default config option without a prompt? > > I thought that you needed different ellipsoids for different parts of the globe. > wgs84 or nad83 may work well for California, but I doubt if they would for Europe. > Ireland works on a Modified Airy Ellipsoid afaik, so I think you're right in saying it needs different ellipsoids for different areas of the globe. What a miss-shapen world we live on. :) Stephen

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RE: [OpenGuides-Dev] locator plugins
by IvorW 28 Jun '04

28 Jun '04

> -----Original Message----- > From: openguides-dev-bounces(a)openguides.org > [mailto:openguides-dev-bounces@openguides.org]On Behalf Of Jo Walsh > Sent: 28 June 2004 00:42 > To: OpenGuides software developers > Subject: [OpenGuides-Dev] locator plugins > > > > an additional piece of data by way of the ellipsoid. This > > needs to be prompted > > for in the setup, and held in the config file. > > i kind of assume it will always be wgs84 - 23 for > Geo::Coordinates::UTM - or nad83 which is centimetres of > difference. this is what gps, the big mapping sites, etc use > - this could be a default config option without a prompt? I thought that you needed different ellipsoids for different parts of the globe. wgs84 or nad83 may work well for California, but I doubt if they would for Europe. > > In terms of metadata, the module needs (and relies on) > latitude and longitude. > > The pythagorean distance finder needs zone, easting and > northing. The plugin > > will provide these via the location method. The distance > finder needs zone, > > easting and northing to be stored in the database. > > i never needed to use the zone, but things will blow up if a > guide spans more than one and gets different spatial references? > as 'easting' and 'northing' rather than os_x / os_y? The zone is just there as a memorandum field. The distance finder only detects locations in the same zone as the place you are searching from. Also, the distance method checks the zone. I guess it could return undef, and allow calling code to use a different distance algorithm - such as one which works off lat/long. I only think this is an issue when we get a guide that spans multiple zones. > > then i think the 2 plugins should be totally compatible, and > i just change mine to use base > CGI::Wiki::Plugin::Locator::UTM, and add the geocoding > method. nice one ivor. Good! That shows my initial idea was sound :). > a further thought! Schuyler objects that distances in metres > and kilometres meant little to people not used to seeing them > / converting between them and yards/miles, e.g. pesky > merkins. i could do metre/mile conversion and change the > distances - or keep it like it is - but it's definitely a question. Sounds like a case for using Data::Dimensions. Ivor.

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[OpenGuides-Dev] openguides-setupdb script
by Osfameron 27 Jun '04

27 Jun '04

Hi, I've attached a setupdb script for OpenGuides created for 2 reasons 1) it seems silly to have to remember the arguments for cgi-wiki-setupdb when you've already input them into a perfectly good wiki.conf file 2) it can input some standard nodes (like Text Formatting Tips, sample licensing etc.) for an OpenGuides distribution. Hopefully should be pretty clear from script and basic POD. Any suggestions? (Tested on Win32 with Mysql and SQLite) -- osfameron

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[OpenGuides-Dev] Error encountered deleting node history version
by Earle Martin 27 Jun '04

27 Jun '04

I just got this trying to delete version 17 of "Wiki Etiquette": DBD::Pg::st execute failed: ERROR: Bad timestamp external representation '' at /home/earle/downlode.org/perl/lib/CGI/Wiki/Store/Database.pm line 572. Might be a CGI::Wiki thing. -- Earle Martin http://downlode.org/ http://purl.oclc.org/net/earlemartin/

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Re: [OpenGuides-Dev] openguides-setupdb script
by IvorW 27 Jun '04

27 Jun '04

----- Original Message ----- From: "Alessio Bragadini" <alessio(a)sevenseas.org> To: "IvorW" <ivorw-openguides(a)xemaps.com> Sent: 27 June 2004 16:02 Subject: Re: [OpenGuides-Dev] openguides-setupdb script > > On Sun, 2004-06-27 at 12:32, IvorW wrote: > > > By the way, I have a Postgres problem with type conversion. How do I force it to use > > a float (or rather a double)? This is a problem with the distance finder on Postgres. > > What's your problem exactly? Typecasting in PostgreSQL is usually done > in the form of > select a::float from... > but please let me know if I can help. > Just uploaded 0.02 to CPAN which now passes the test on Postgres as well Thanks for the info.

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[OpenGuides-Dev] Bio Mapping Together
by Christian Nold 27 Jun '04

27 Jun '04

Hi, Quick reminder - Bio Mapping is now live at the RCA Degreeshow in London. Please come along to the show and borrow one of the devices to join in the Collaborative Emotion Mapping. You can also catch the project on-line at www.biomapping.net. New maps will be uploaded as the emotion map grows. The event will go on till next Sunday - 4th of July. (closed July 2), 10am to 6pm daily. Late night opening on the 1 July until 10pm. Royal College of Art, Kensington Gore London SW7. Interaction Design http://www.biomapping.net/map.jpg -- Best Christian www.softhook.com www.mobilevulgus.com

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