Indexes of lists

1

I am pretty sure there is a simple answer to this- I just can’t figure out what it is…!
I need to take the index of a list and use it as an identifier for a grid of points

In the example shown below- I need to extract the index of the highlighted point [5,2] and convert it to a string indicating the column/row. So the 5th column & 2nd row --> X5 Y2

I have tried IndexOf, AllIndicesOf etc with no success

thank you in advance

20160610 point array.PNG1870×839 75.9 KB

2

How about:

2016-06-10_16-01-09.png1410×712 38.4 KB

3

thanks for the very quick reply Dimitar.

I’m not sure if I have explained myself very well- perhaps I mean ‘key’ rather than index.
I would like to generate the XY for each point, not just one of them

At the risk of complicating things- to briefly explain the end goal:

  • by feeding a URL to a GIS server, I am extract aerial images of a particular area, defined by coordinates (and some other stuff such as coordinate system, number of pixels, image type etc)
  • I am using Dynamo to generate the coordinates for a mosaic of images of a certain size & number of rows & columns
  • The output is a file containing the image name, plus the concatenated URL with coordinates etc

For example:
http://maps.six.nsw.gov.au/arcgis/services/public/NSW_Imagery/MapServer/WMSServer?LAYERS=BestImageryDates&FORMAT=image%2Fpng&VERSION=1.1.1&REQUEST=GetMap&STYLES=&SRS=EPSG%3A28356&BBOX=334363.000000,6252655.000000,334463.000000,6252755.000000&WIDTH=800&HEIGHT=800

is part of the Sydney Harbour bridge.

For the image name- I would like it to be ‘X5 Y8.png’ to indicate where it sits in the image array, rather than sequential number such as ‘16.png’

Pasted image800×501 10.7 KB

I have attached the graph and output.

thank you

AndrewAerial image extractor.xlsx (11.9 KB)

aerial image extractor.dyn (26.2 KB)

4

The format of the output can be altered to suit your requirement…

20160610-1.png882×376 24.3 KB

5

thanks Vikram, that is fantastic- exactly what I needed
Thank you for your help Dimitar

Results below:

Pasted image1808×736 1020 KB

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6

[quote=“Andrew_Hannell, post:5, topic:4431”]
exactly what I needed
[/quote]Might you share your final DYN?

7

Sure

7pm on a Friday here- graph is a bit of a mesh from a rush
Time to go home, but I will tidy it up & share next week…

The graph is quite specific to the Land & Property Dept of New South Wales GIS system,but could be adapted for any WMS server

Andrew

8

I have attached the tidied up graph and Revit family.
aerial image extractor v5.dyn (61.1 KB)

1315×836 71.4 KB

map grid.rfa (300 KB)

Notes:

  • Web Mapping Service (WMS) servers provide data such as aerial imagery, cadastral (boundaries) or land information
  • Many authorities, government departments etc provide data using this service
  • GIS applications or Map3D or Civil3D can bring in this data dynamically
  • Applications such as Sketchup can bring in basic Google aerial imagery, or Infraworks can get data from many sources- but the WMS data is often better quality or contains more information (such as cadastral, survey marks etc

This data is defined in the URL- refer above
I built this Dynamo graph to generate the image URLs based on a base coordinate, grid size and number of rows/columns, and name the image based on the row/column location.
Refer https://youtu.be/XDbJ_JFnK0s

Each WMS server is a bit different- need to play around with the URL layers, file format etc and also enter the correct EPSG coordinate zone.

I used Pentaho to download the images and name them correctly. Tested up to 100x100 rows & columns- takes several hours to generate/download the images.

It is not super-accurate (speak to a surveyor or GIS person & they will talk about geodetic projections etc) but at least you get images with known real world dimensions & corner coordinates, and these can easily be built into a mosaic.

Hope it helps

Andrew

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