How to apply 'streetside' to multiple edges?

[coreymurray]

Hi!

I have many, many parcels.

Is there a way to assign 'streetside' to edges, other than double clicking and selecting Shapes > Set Street Edges

Any info would be greatly appreciated!

Cheers

Corey

[MatthiasBuehler1]

check my other reply in your other thread here :
http://forums.arcgis.com/threads/61181-How-to-define-the-street-side-to-do-the-setbacks-in-static-sh...

* * *

in general, a generic description of your process is tricky.

if you have multiple parcels inside 1 block, theoretically all edges are facing a street simply because they're all inside streets. thus, you have to create a script which distinguishes between the states if a neighboring parcel edge is closer than an actual street.

for this, you can write a Python script, which I'd recommend in your case.

let me know if this helps so far.

in case you decide to write such a script on your own, I can help you with starting.

matt

[coreymurray]

Hi Matthias,

Thanks for the reply �?�

I don't know python, but i'm always keen to learn...

OK, in that kind of script, what kind of criteria would define street edge? If the distance from the edge to street is greater than the distance to other edges of the same parcel?

In a lot of cases the street edge(s) is the only edge(s) that do not overlap or lie on top of another edge in the same block... could that be a unique property we could leverage i.e. streetside = edges that are not touching parcels from the same block.

Sorry about the lay-speak!

Cheers

Corey

[MatthiasBuehler1]

it's a very tricky task to express this generically ..

maybe you start best with a screenshot that shows a part of your dataset with both street center lines and actual footprints.

based on this, the criteria can be found better..

can you post such an image ?

[coreymurray]

Hi Matthias,

Thanks so much for your reply.

I'll try and get some images up in the next couple of days.

Cheers

Corey

[coreymurray]

Hi again �?�

I've attached some images of my scene, and also the data i have used in a .zip file.

Hope this is of some use.

Kind Regards

Corey

[MatthiasBuehler1]

ok.

questions :

are you familiar with the difference between the concepts of the 'First Edge' vs. 'StreetEdge' ?

a] the First Edge (just 1 edge per shape) usually defines the front side of the lot. a default lot, that would usually ( except for corner lots ) be the shorter edge.

the Dynamic City Layouts ( CityEngine's Block Subdivision system) automatically sets that First Edge on the widest street edge. If on a corner lot ( 2 streets ) both streets are equally wide, the longer edge is chosen.

b] the Street Edges can be multiple edges per shape. E.g. lots with curvature have a lot of small segments which may or may not be sitting along a street. thus, EACH edge has to be checked whether it's facing a street or a neighboring edge.

since this 'correlation data' between shapes and graph lines does not exist we have to write a script which does that for us. That's not really easy because not in each case ( each edge ) we can easily say what is what.

so far so good ?

[coreymurray]

Thanks Matthias

Yep i think i'm still with you...!

[MatthiasBuehler1]

ok, I have attached one of your images with 2 colored lots to explain things.


1]
red lot :
the street egde should also be the first edge ( -> both need to be set, because the first edge defines the front of the building )
'usually', the first edge is a subset ( 1 edge ) of the shape's street edges.
but what happens if the shape were set back 5 meters ( black fat new line ) : would it still be considered as a street edge so far away from the street ?
you already see that you have to define thresholds for certain things.

2]
green lot : [ let's say the curve has 4 segments. ]
we agree that this lot's got 6 street edges, but which would be the First Edge ? in the last post, I've mentioned that in this block subdivision pattern, it usually is the shorter side, thus the shorter edge. but here we have multiple possibilities because we have multiple possible segments, a longer one ( the one we'd choose by our human intuition ) and maybe 2 of the corner segments which also face the street at a small enough angle.
you see now that you need new thresholds for a] 'street facing angle' and 'minimal Edge Length To Be Counted As First Edge'. e.g. if one tiny edge is facing the street on a better angle than the much longer edge right next to it, we'd want the longer one.

3]
in general, you see that we need to :
a] find the abstract concept behind the geometry to be able to quantize each edge individually and compared to each other
b] create the code which does the above for us


are you familiar with vector math and 'scripting in general' ?