Bob, The application that Sarah asked about would be very applicable in situations such as disaster planning (spill sites, contamination areas, etc) and telecommunications (uniform gain in the strength of a tower signal or broadcast area), just to think of a few.
-Ross E. Bagwell GIS Manager Universal Access Inc -----Original Message----- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] Sent: Thursday, January 15, 2004 12:26 PM To: Hooper Sarah Cc: '[EMAIL PROTECTED]' Subject: Re: MI-L Poly size increase Hi Sarah To answer your question well it would certainly help to know why the area of the polygon needs to grow by a value and indeed what the polygon represents. I have listed below one technical solution but before that I would just like to show some caution by suggesting for most applications this would be a dangerous assumption. If a planning authority decided to allow a 10 per cent growth in housing it is highly unlikely they would allow a uniform growth. There would be many constraints. Physical constraints such as rail, river and road and environmental considerations would make the following a meaningless solution. The growth is just as likely to be a bubble on the side of the existing area as a uniform growth as detailed below. With that reservation in mind:- One solution... Find the existing area by one of MapInfos alternatives ... eg using select tool select object. In a similar way find the perimeter of the object. Multiply the area by the percentage increase to get the increased area. Divide the increased area by the perimter to find a buffer value. Buffer the object with the offset as calculated. This solution to be very accurate would need to be iterative. The new object would not exactly be the correct new area because on obtuse angles around the perimeter it will increase too much and on acute by not enough. However if say you wanted to increase by 10% and your first calculation for the offset is say 9.2 metres and this gives a real increase of 11% your second iterative solution for the offset would be 9.2m x 10/11. ( hope this makes sense ). This technical solution is of course based on increasing the object out from its centre uniformly by a constant buffer size and I cannot straight off think of an application where this would be apporopriate! Regards Bob Quoting Hooper Sarah <[EMAIL PROTECTED]>: > Hi, > > I am trying to increase polygon sizes by a percentage value. How do I go > about this? And is there a way to increase many at once? > > Thanks in advance, > Sarah > > > > > **************************************************************************** **** *** > The contents of the e-mail and any transmitted files are confidential and > intended solely for the use of the individual or entity to whom they are > addressed. Transport for London hereby exclude any warranty and any liability > as to the quality or accuracy of the contents of this email and any attached > transmitted files. If you are not the intended recipient be advised that you > have received this email in error and that any use, dissemination, > forwarding, printing or copying of this email is strictly prohibited. > > If you have received this email in error please notify > [EMAIL PROTECTED] > > This footnote also confirms that this email message has been swept for the > presence of computer viruses. > **************************************************************************** **** *** > > > --------------------------------------------------------------------- > List hosting provided by Directions Magazine | www.directionsmag.com | > To unsubscribe, e-mail: [EMAIL PROTECTED] > For additional commands, e-mail: [EMAIL PROTECTED] > Message number: 9923 > > --------------------------------------------------------------------- List hosting provided by Directions Magazine | www.directionsmag.com | To unsubscribe, e-mail: [EMAIL PROTECTED] For additional commands, e-mail: [EMAIL PROTECTED] Message number: 9927 This communication contains information from Universal Access, Inc. (or its affiliates) which is confidential and may also be privileged. It is for the exclusive use of the intended recipient(s). If you are not the intended recipient(s), please note that any distribution, copying or use of this communication or the information in it is strictly prohibited. If you have received this communication in error, please notify the sender immediately and then destroy any copies of it. --------------------------------------------------------------------- List hosting provided by Directions Magazine | www.directionsmag.com | To unsubscribe, e-mail: [EMAIL PROTECTED] For additional commands, e-mail: [EMAIL PROTECTED] Message number: 9930
