topic Re: linear interpolation between wind speed contours in ArcGIS Spatial Analyst Questions

linear interpolation between wind speed contours

kathy71jones — Sun, 15 Oct 2023 01:57:04 GMT

I have created wind speed contours from wind speeds estimated by processing weather station data. I would like to generate rasters with values that are interpolated linearly between these contours. What I can find in the ArcGIS Pro toolbox is the Topo to Raster tool that is specific to the characteristics of topographic data and does not seem to linearly interpolate. What am I missing?

Thanks for your help.
Kathy

Re: linear interpolation between wind speed contours

MarkBoucher — Sun, 15 Oct 2023 12:31:04 GMT

Kathy,

I did something similar for rainfall contours using ArcMap and Spatial Analyst. I documented it here.

https://www.contracosta.ca.gov/DocumentCenter/View/3914/Mean-Seasonal-Precipitation-Raster-From-Dwg-B-166-PDF?bidId=

It was a while ago, but after looking at the document, I now recall I made a raster from the manually created (digitized) contours, from the raster generated finer contours, checked the accuracy of those finer (smaller interval) contours. Then I manually interpolated between the initial manual contours where needed by creating lines between the initial contours and then drawing new contours by clicking the midpoints of those lines. Tedious, but it worked.

Possibly what you need is somewhere in that process. ArcPro may have a simpler tool.

Mark

Re: linear interpolation between wind speed contours

MarkBoucher — Mon, 16 Oct 2023 04:30:06 GMT

If you can create a raster from your contours, you can create contours at any interval from that raster. What I did was create supplemental contours by manually interpolating halfway between the starting contours to train the raster to create contours that I agreed with. So there was still some subjectivity involved. - Mark

Re: linear interpolation between wind speed contours

kathy71jones — Mon, 16 Oct 2023 14:03:45 GMT

Hi Mark, I'm not sure I understand. How do you train rasters?
Ultimately what I want is a raster field with values obtained by linear
interpolation from my contours.
Kathy

Re: linear interpolation between wind speed contours

MarkBoucher — Mon, 16 Oct 2023 15:43:36 GMT

Kathy,

Sorry. By "train" I meant that after I create the raster from contours and then create the contours at smaller intervals, I see if the newly created contours make sense. If not, then I add intermediate contours and repeat the process. This adding of additional intermediate contours is what I call "training". If you look a the document I linked, you will see some maps with circled areas that I felt I needed to add more intermediate contours to "train" the raster to output more reasonable contours.

Hope this makes sense...

Mark

Re: linear interpolation between wind speed contours

kathy71jones — Mon, 16 Oct 2023 18:09:45 GMT

Mark, the document you linked
https://www.contracosta.ca.gov/DocumentCenter/View/3912/Verification-of-the-District-Standards-11-07-2011-PDF?bidId=
is primarily about rainfall distribution curves. I didn't see anything
about maps with precip contours. But Appendix C is blank.
Is there a different document about that?
Thanks, Kathy

Re: linear interpolation between wind speed contours

MarkBoucher — Mon, 16 Oct 2023 18:54:23 GMT

Sorry Kathy.

I had noticed that myself and quickly edited the post with this correct link. Possibly you were responding via an email reply and not looking at the esri Community page. Here's the correct link again.

https://www.contracosta.ca.gov/DocumentCenter/View/3914/Mean-Seasonal-Precipitation-Raster-From-Dwg-B-166-PDF?bidId=

Mark

Re: linear interpolation between wind speed contours

kathy71jones — Tue, 17 Oct 2023 19:54:04 GMT

Hi Mark, You're right--I was using the link in the email. Thanks for the
corrected link. So you used the Topo to raster tool to create a raster
field to interpolate your contours of precip depth. And it looks like you
found that there were anomalies in that raster field where the precip
values were inconsistent with the precip contours. I found the same thing
when I used the Topo to raster tool to interpolate my wind speed contours.
It looks like you corrected your raster interpolation by adding more
contours to have a finer contour interval.
I'm wondering if I can eliminate/reduce my raster anomalies by adding more
points to my existing contour polylines. The curves are relatively smooth
so are defined by points that are relatively far apart.
But I am also wondering about the value of the IDW power used in Topo to
Raster. For two points on a line power=1 results in a linear interpolation.
I haven't found any information about the IDW power used in Topo to raster
but in another ArcGIS tool power=2 was the default. Will that provide
linear interpolation between contours?
Thanks, Kathy

Re: linear interpolation between wind speed contours

MarkBoucher — Tue, 17 Oct 2023 23:17:54 GMT

Kathy,

Sorry, I'm not aware of the IDW options/effects in the topo to raster tools. Maybe someone listening can address that.

Mark

Re: linear interpolation between wind speed contours

RonaldHaug — Wed, 13 Dec 2023 06:00:40 GMT

Hi Kathy,

I think this windspeed interpolation is pretty neat.

Are you able to account for direction, too?

https://earth.nullschool.net/#current/wind/surface/level/orthographic=-120.00,0.00,293