DEM Raster Manipulation

[Halina Pyzdrowski]

Hi all,

I am working with a series of DEM rasters for North Carolina to complete ACPF analysis. Here is the link to the metadata. I am trying to evaluate if this DEM will work for my analysis, and if so, how I will need to resample the data for my purposes. The coordinate system is NAD 83. I believe the horizontal and vertical units are in meters, but I am not positive. I also believe that the z-units will need to be converted to cm.

Thank you,

Halina 

[Asell, Andy]

10 meters will be too coarse.  I would use one of the datasets provided here, likely the 3.25 foot dataset (roughly, but not exactly 1m pixel resolution). You'll definitely need to convert the Z from feet to cm. Without seeing the files' projection and pixel resolution, I'm not sure what you'll need to do to get the pixel resolution into meters. But expect to address that, as well.  Andy 

Andy Asell 

GIS Analyst - Forestry, Agriculture, & Natural Resources 

Land Quality Bureau - GIS Section

Department of Natural Resources

6200 Park Ave, Ste 200, Des Moines, Iowa 50319 

515-250-3303 (mobile)

andy....@dnr.iowa.gov

www.iowadnr.gov

 

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[Sandoval-Green, Claudette [A&BE]]

See if this helps:


The horizontal resolution of the DEM must be whole meters (i.e., no floating points, use integers).

▪ Any z-unit is accepted, but z-factor must be known.

▪ Centimeter integer z-units work well (z-factor will be 0.01).

o If vertical = centimeters, and horizontal = meters, then z-factor = 0.01

o If vertical = meters, and horizontal = meters, then z-factor = 1

▪ The ACPF core data is in UTM.

▪ The DEM extent should be the same as the buffered watershed boundary.

▪ Listen to the Get Elevation Dataset at 23:00 minutes in the YouTube video (https://youtu.be/WumpHVmkkCQ?si=5zCmf3tAmrmMcJVW

You will learn about:

o Resampling cell size to reduce processing time.

o Converting vertical units from feet to centimeters using the Raster Calculator.

o Converting floating points to integer using the Raster Calculator.

o A reminder to always use the buffered boundary to Extract By Mask or in ArcGIS Pro use (first

highlight the raster in the Contents pane) Data > Export Raster.

 

Claudette M.J. Sandoval-Green, MGIS
GIS Database Development Specialist and Supervisor

Research Scientist II
Dept. of Agricultural & Biosystems Engineering | 2333 Elings Hall
IOWA STATE UNIVERSITY

Daily Erosion Project (DEP)
Agricultural Conservation Planning Framework (ACPF)
Web CV

 

Email: clau...@iastate.edu

Phone: (515) 294-4608 

  
 

 

From: 'Halina Pyzdrowski' via ACPF Forum <acpf-...@umn.edu>
Sent: Wednesday, November 13, 2024 11:26 AM
To: ACPF Forum <acpf-...@umn.edu>
Cc: Andy Asell <andy....@dnr.iowa.gov>; ACPF Forum <acpf-...@umn.edu>; Halina Pyzdrowski <hpy...@ncsu.edu>
Subject: Re: [ACPF Forum] DEM Raster Manipulation

 

Thank you. Yes, the conversion of the pixel resolution from feet to meters is where I am getting stuck. If others have guidance on this, please let me know.

To view this discussion visit https://groups.google.com/a/umn.edu/d/msgid/acpf-group/0040bc95-20df-4219-90e5-b92a8880a670n%40umn.edu.

[Halina Pyzdrowski]

Thank you. Yes, the conversion of the pixel resolution from feet to meters is where I am getting stuck. If others have guidance on this, please let me know.

On Wednesday, November 13, 2024 at 12:13:16 PM UTC-5 Andy Asell wrote: