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dyalsjas
157 post(s)
#18-Feb-19 13:46

I'm once again trying to output a slope raster with values reflecting percent (grade) instead of degrees.

I ran the standard slope transform, then the tangent transform on the resulting slope image; modified to multiply the output of TileTan by 100 to get percentage or grade.

The output of the Tangent query does not have values close to what I'm expecting.

Am I missing something obvious?

Tim helped me with a similar process last year, but as I recall, part of the problem was converting the default output of radians to degrees before calculating the tangent / percentage values.

I've attached a small .mxb with data and my queries so far.

Would still love the ability to select the output values of the slope transform to be degrees, radians, or percent.

Attachments:
Slope_Percent.mxb

adamw


10,447 post(s)
#18-Feb-19 14:13

Tan / TileTan take radians (that's in the query builder description for Tan, we'll have that in the API doc as well).

Change the call to TileTan in Slope_Percent_Query to:

--SQL9

...

  CASTV (((TileTan([Tile] * Pi / 180)) * 100) AS FLOAT32)

...

We'll consider adding a control to the Slope transform to specify the output format.

dyalsjas
157 post(s)
#18-Feb-19 14:32

Thanks Adam.

I obviously forgot to look at the documentation for the Tan function (again ).

Now I'll look back at what Tim helped me with in April so I can aggregate the slope into categories for analysis.

I don't need to Trace Areas this time so it should be easier.

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