Can be done! I try the following procedure and it worked. Create a new table call overlaps with at least 2 columns, called ID, and count_overlaps
Add the layer on top of your polygon layer, make sure it's editable Select all the objects on the layer where polygones overlaps. Go to the menu objects, select check region. Make sure the overlaps is selected. This will create polygons for the commun part that overlaps on the layer "overlaps". Once this is done you can now add a count of how many polygons overlaps underneet each sections Now you need to identify the polygons. Use update column to update the column ID, get value from table overlaps, Value is rowid. Rowid will put a different number from each ovelapping region. We'll use it to make a query and count the number of time a polygon is under it... Use SQL select. Select the layers ovelaps and the layer where your original polygons (let's call it areatest for now, where conditions overlaps.obj within areatest.obj, select column overlaps.id, count(*), Group by columns overlaps.id, into Table Named counter_of_polygon You have a list of id with the number of polygons under it! You now can update the table of ovelaps with those values store in that request. Go to update again, table to update is overlaps, column to update is count_overlaps, get value from table where you join both table coount_of_overlaps and overlaps using the ID fields to link them, calculate value of Count You now have a new table of region having data associated to it giving you the number of polygon that overlaps at that specific location. You can then choose to make a thematic or individually make selection by value and manually change the color according to the number of overlaps You can modify thais procedure to add other column like amount ofarea that overlaps, etc. Also you can add information on you existing polygons by counting how many overlaps there are and add the values from the overlaps count. And so on... If the overlapping polygons are on separate layers, that procedure couldn't be use. Then you'll have to program something more elaborate. One easy way is to do it in that situation is to create a temporay file where you copy all the polygons from separate files into a single file leaving your orginals intact. Once you are done creating the overlaps region, just get rid of that copy.. Voila! GH -----Original Message----- From: Burchfield, Robin 10088 [mailto:[EMAIL PROTECTED] Sent: July 14, 2004 11:45 To: [EMAIL PROTECTED] Subject: MI-L Thematically mapping ovelapping polygons Hello Lisiters I need to complete a series of maps for different areas and have hit a problem. For each area I have a number of polygons (ranges from 10-35) that partially overlap one another. I wish to show these polygons all on one map but with some kind of indication as to the weight of separate polygons under each overlapping section e.g. if I have an area where 5 polygons overlap I would like this to be shown darker than an area where only two polygons overlap. I hope this makes sense and if so does anyone have any ideas on doing this. TIA Robin Burchfield Mapping & Data Officer Surrey Police Mount Browne Sandy Lane Guildford GU3 1HG Tel: 01483 482357 E-mail: [EMAIL PROTECTED] Internet communications are not secure and therefore Surrey Police does not accept legal responsibility for the contents of this message. This email and any attachments may be confidential. They may contain privileged information and are intended for the named addressee (s) only. They must not be distributed without our consent. If you are not the intended recipient, please notify us immediately and delete the message and any attachments from your computer, do not disclose, distribute, or retain this email or any part of it. Unless expressly stated, opinions in this email are those of the individual sender, and not of Surrey Police. We believe but do not warrant that this e-mail and any attachments are virus free. You must therefore take full responsibility for virus checking. Surrey Police reserves the right to monitor all email communications through their networks. --------------------------------------------------------------------- List hosting provided by Directions Magazine | www.directionsmag.com | To unsubscribe, e-mail: [EMAIL PROTECTED] For additional commands, e-mail: [EMAIL PROTECTED] Message number: 12618
