topic Re: TIN to Raster in Geoprocessing Questions

TIN to Raster

KONPETROV — Fri, 06 Nov 2015 11:40:31 GMT

Hi, I want to use 3 different series of Data in the form of TIN for a viewshed analysis. I thought to convert them to raster because as I saw, I cannot do a viewshed in the form of TIN. My problem is that when I convert TIN to Raster from the 3D Analysis toolbox, although the resolution in TIN is 10meters, in Raster is almost 30meters. Why is that? Can't i convert it to raster and to have the same resolution? The analysis at my raster is being made for 30 meters resolution or for 10 meters at last?

Thank you very much

Re: TIN to Raster

LukeSturtevant — Fri, 06 Nov 2015 11:57:25 GMT

What spatial reference are you using? Did you set the sample distance to 'CELLSIZE 10' ?

Re: TIN to Raster

KONPETROV — Fri, 06 Nov 2015 12:10:21 GMT

oh no. I will do that now and i will post my results

Re: TIN to Raster

KONPETROV — Fri, 06 Nov 2015 12:12:15 GMT

Well the problem is that I have the option Cellsize 28.8839. Can i change it to 10? Why it shew a cellsize at 28.8839 by default? Won't I affect something if I change it?

Re: TIN to Raster

LukeSturtevant — Fri, 06 Nov 2015 12:16:43 GMT

Yes you should change it to CELLSIZE 10 if you want 10 meter cells. Unless your spatial reference has a linear unit of feet then that will produce a cell size of 10 feet.

Re: TIN to Raster

NeilAyres — Fri, 06 Nov 2015 13:11:03 GMT

And you may want to check the environment settings for the extent, and can set the cell size there.

If creating several rasters from different tins (but over the same area), for the benefit of down stream processing, get them all to line up correctly (pixel co-registration), by defining, using the environment variables, the exact extent and pixel size, and use the first as a snap raster.

Re: TIN to Raster

KONPETROV — Fri, 06 Nov 2015 13:44:52 GMT

My main concern is, if it is totally arbitrary to define by myself the cellsize, because when I chose the cellsize its value shows 28.8839 and to an another TIN with bigger resolution it rises to 30.3111!!

Because with that logic I can also put the cellsize to be 1 meter also arbitrary, but it won't correspond to reality!!

Re: TIN to Raster

LukeSturtevant — Fri, 06 Nov 2015 13:56:56 GMT

The computed cellsize the tool picks is the same computation it does as if you were to pick OBSERVATION. It just does a division by 250. You can arbitrarily decrease the cellsize it picks for you because it will interpolate the cell values but you just have a better resolution raster for your viewshed. What you wouldn't want to do is increase the cellsize because then you will lose data in the raster interpolation.

Re: TIN to Raster

NeilAyres — Fri, 06 Nov 2015 15:22:24 GMT

Somewhere it is detailed that the default pixel / cell size is set by dividing the range of the extent by 250.

That's how you get ~30m pixels.

Re: TIN to Raster

KONPETROV — Fri, 06 Nov 2015 15:34:36 GMT

ok, very well, and the max number of points in the viewshed tool is 16 points?

Re: TIN to Raster

JayantaPoddar — Sat, 07 Nov 2015 09:44:57 GMT

Hi Kon,

Did you try changing the environment setting of the tool?

Re: TIN to Raster

DanPatterson_Retired — Sat, 07 Nov 2015 10:16:26 GMT

Yes as I stated earlier. The link to the help topic is in your viewshed thread.

Re: TIN to Raster

KONPETROV — Sun, 08 Nov 2015 17:09:20 GMT

Yes, the default were the numbers I wrote above

Re: TIN to Raster

LukeSturtevant — Tue, 10 Nov 2015 12:09:55 GMT

Kon,

If you are still having this issue, maybe you would consider uploading one of your tins so that we can better understand what is happening here.

Re: TIN to Raster

KONPETROV — Wed, 11 Nov 2015 20:36:09 GMT

Luke thanks for your interest. I don't have that issue, i just put the resolution i wanted at the cell size. My wonderies are just when I have a TIN from 10 meters resolution elevation data, and I create a raster from that TIN with resolution bigger than 10 meters, for example 1meter resolution (that I define every time), what are the restrictions of that step, you know the theory. This is mainly my problem, the theory beyond that. Thanks a lot.

Re: TIN to Raster

DanPatterson_Retired — Wed, 11 Nov 2015 22:47:38 GMT

Tin to raster How TIN To Raster works—Help | ArcGIS for Desktop

raster to TIN How Raster To TIN works—Help | ArcGIS for Desktop

In either case, either data structure is only as good as your input data, and that includes considerations of accuracy and in the case of precision you also need to look at spacing between the intervening point (if variable), the type of interpolator or aggregator in the case of rasters.