determine the radius of a curvature from GPS points ?

[xavierberlo]

Hello,

I have a shapefile of gps positions (sucession of points, with X Y Z data) of hundreds of kilometers of road

and I'd like to know if it possible with ArcGis 10 to determine the radius of each curvature.

Example : I have one segment of a road represented by 100 gps points and I'd like to draw the curves and measure the radius of each curvature.

Is there a tool for that ? Or a script ?

I hope I will be able to find the help I need here because I'm lost.

Thank you

[xavierberlo]

Ohh, I'm not allowed to install any sharing screen program. This has been blocked by the company a while ago (for security purposes i suppose).

What is weird though is that, ever since I changed the projection, the script doesn't seem to work anymore. Even when I changed it back to the way it was before I modified it.

I understand it's time consuming to try to help me and I'm sry for the trouble.I do understand if you don't have the time for it right now. We all are busy .

[RiyasDeen]

Not a problem at all xavier. This is interesting enough to keep me hooked.

Can you send across your shape file?

[xavierberlo]

Hello,

Here it is !

[RiyasDeen]

Worked straight away for me.

Sharing the whole deck again, including your new shape files. Please be mindful of circleShapeFile @ line 15 in radius of curvature.py, you should point it to location of Circle_project shape file.

[xavierberlo]

Well it works ! It's odd. I don't know why it didn't earlier. I must have forgotten to change something.

Thank you very much.

Results seems to be close to the curve calculator tool from arcgis.

[RiyasDeen]

Hi Xavier,

Glad it worked!

[JimBarry]

(side note: ArcScripts still being built. got a personal update from the developer last week; things are moving along)

[DanPatterson_Retired]

Great Jim...they are starting to pile up

[DanPatterson_Retired]

Everyone has pictures except me

[DanPatterson_Retired]

In the last image sent by Riyas, you are picking too many points, you are getting points of the tangent thingy (can't remember what it is called Xavier) you should be able to chose about 60% of the points that you have chosen.  A good test is to visually eye the centre of the arc (there are other methods)  then select some points, do the results then gradually trim points off either end of the selection.  In theory, there should be a place where point selection doesn't improve radius estimates and the only deviations will be due to scatter normal (90 degrees) to the "real" arc.  If memory serves, this scatter has a great role upon the estimates of the radius.  I am still trying to track down copies of the paper and a thesis which deals with this issue.  I can't find my copies and my colleague isn't back yet.