collapse

* Forum Staff

PeterC admin PeterC
Administrator
admin webmasterOPS
Administrator

Author Topic: Creating a Feature Layer containing points  (Read 283 times)

PeterC

  • Administrator
  • Member
  • *****
  • Posts: 382
  • Passionate about my one-place study
    • View Profile
    • Holywell-cum-Needingworth History
Creating a Feature Layer containing points
« on: 21 November 2016, 17:26:40 »
If you do not already have a separate "Features" file listing all your Features, then to create a Feature Layer containing Points you need to create a CSV file with at least the following fields:
  • shorttext
  • Lon(X)
  • Lat(Y)
(Note that if you do already have a separate file of Features, then the file for your Feature Layer can be even simpler - see the note below.)

You can create a suitable file by going to your OPS in M4OPS and then:
  • click on New, under Modifiable Feature Layers - this will create a new blank Modifiable Feature Layer (MFL), and open some more buttons
  • if it is not already selected then click on Point to select this option
  • on the map, click where you want your first point
  • you will be shown a form where you can enter its "short text" - use this to name the point
  • click on Save to save this form, then Close to close the form
  • click where you want your next point, again enter its  "short text", Save and Close the from
  • repeat as often as you want (but bearing in mind that this is a prototype, do not spend too long entering large amounts of data as it might all disappear)
  • at some point enter a name by which this Modifiable Feature Layer (MFL) will be known
  • at any point click on Save to save this Modifiable Feature Layer (MFL) in M4OPS (you can do this as many times as you want)
  • if you wish to modify the positions of any of the points then click on Modify, and then drag the points to exactly where you want them
  • if you wish to enter, or change, the properties of any points then click on Alter and fill in the form - remembering to Save the form before you Close it
  • (note that you can enter different colours, circle radiuses, pin types and symbols for each point, but you do not need to enter any of them)
When you are happy with the details of your features (particularly their "geometry" (ie where they are) you can download a CSV file containing the data onto your own computrer. To do so make sure you have chosen an MFL name (this is the default filename) and then click on CSV.  You will be given the opportunity to choose where the file is downloaded to, and its name.

If you open this csv file (eg in a text editor or Excel) you will see that it contains fields for shorttext;Lon(X);Lat(Y) - all of which must be there; and also the optional fields description;datestart;dateend;pin;symbol;color;radius. Rather than being "comma-separated" the fields are separated by semi-colons, but we still call it a CSV file, and it has a .csv "extension".

You may edit this file, entering new rows and changing values of fields as you wish - as long as the number of semi-colons on each row is the same.  Using semi-colons rather than commas to separate fields enables individual fields such as description to include commas, but they must not include a semi-colon.  If you wish to get accurate coordinates [Lon(X);Lat(Y)] for a point manually the easiest way is to use the "M4OPS csv" option in the "no lat/lon" drop down, top left. Alternatively, you may also find it easier to add to, modify and alter the file as a Modifiable Feature Layer within M4OPS and then download the csv file again.


It is very helpful to have a separate file listing all your Features, which typically contains at least the fields featureid;shorttext;Lon(X);Lat(Y).  This file can be created from any Feature Layer (eg created as above) by adding featureids. When you do have such a separate "Features" file, the minimum that is required to create a Feature Layer is just to list the featureids.

 

mapping4ops.org is a Society for One-Place Studies project supported by Grassroots Giving from Skipton Building Society
Glossary | BBCodes | Feedback