Creating surface from .adf file - Scale of Coordinate system is off

[Anonymous]

I'm having an issue with scaling that concerns my coordinate system while creating a surface from a .adf file (NED Data). The file is a 1x1 degree tile with elevations in meters. I had to convert the file from meters to feet which I did by exporting the XML and then loading it into an imperial file successfully with each file set to the correct coordinate system. My issue is the scaling of the file itself. The 1x1 degree grid comes in as 1'x1', and the coordinates are correct within that tile. The issue is this 1x1 degree tile is not 1 square foot and I need the scale to be in a real world setting to lay out other features on the surface to scale. Does anyone have any experience with this or have a suggestion on how to adjust the CS or file to make the distances accurate? In the real world the distance between latitudes is something like 360,000 feet, not 1.

I have already tried scaling the surface but this obviously then makes a huge discrepancy with the coordinates within the file, since they align with the 1'x1' tile. Any help is greatly appreciated since I can not move forward with my design without the correct distances between the lat/longs. 

Thanks.

[Anonymous]

Mderr,

Glad to hear. Would it be possible for you to try to use the .adf files I provided above to see if it works as well? I tried the same process that you mentioned and it is still coming in as a 1' x 1' grid. I'm not sure if it's another setting I might be missing on my end.

Thanks a lot.

[Anonymous]

try these links

metadata:  https://www.sciencebase.gov/catalog/item/5311fa4ce4b0d490f4ab440e

full download: https://prd-tnm.s3.amazonaws.com/StagedProducts/Elevation/13/ArcGrid/n46w111.zip

if those don't work you may have to access it of the viewer

https://viewer.nationalmap.gov/basic/

go to datasets -> elevation products (3DEP).  i use the 1/3 arc-second dem in arcgrid format

the data is in nad83 lat/long decimal degrees

[AllenJessup]

Thank you. I'd found that in the last attachment from the OP. I think the key phrase is "These data are distributed in geographic
coordinates in units of decimal degrees". Not sure what to use as an input CS yet.

[AllenJessup]

This is a good source http://nationalmap.gov/3DEP/documents/NED_DataDictionary.pdf

I opened the PRJ.ADF file in notepad and see:

Projection    GEOGRAPHIC                                                       
Datum         NAD83                                                            
Zunits        METERS                                                           
Units         DD                                                               
Spheroid      GRS1980                                                          
Xshift        0.0000000000                                                     
Yshift        0.0000000000 

So we have to see if we can find a CS to match. I'm working on this in bits and pieces as I do other work.

[Anonymous]

which coordinate system are you trying to match to.

Based on the file you sent your right between CA83-IV and CA83-V.  The split seems to be at the kings county line. north is 4 south is 5.

you're also using 1 arc second which is going to be pretty rough results (about 100 ft x 100 ft grid)

I'll try running it over lunch and see if i have any luck.

[AllenJessup]

The CS the OP has set in the ADF Surface.dwg is NAD83 / BLM 14N (ftUS)

[Anonymous]

I have the larger 1/3 arc file I was just trying to use the smaller sized to make sure I could get the scaling to work properly with the CS. I also just tried to use the files you provided with the state plane settings you had and again it came in only as a 3' x 3' block, since it was inserted as meters. Yours came in at the correct real world scaling or was it this sizing as well?

Thanks

[Anonymous]

Allen,

I have tried to import the .adf within multiple different coordinate systems. For some reason regardless of what I do it will only be inserted as a 1' x 1' or 3' x 3' grid block. After providing that file earlier I have tried using state planes and still have no luck getting it scaled correctly.

Even using Mderr's files that he said worked properly it still came in at the very small scale. I've attached that drawing as well with just the basic point group loaded that came in as a 3' x 3' block. , maybe there's a different setting I'm still missing?

Thanks.

[Anonymous]

i ran it over lunch and got a good result.  Input coordinates for the .adf file set to LL83.  Output coordinates set to CA83-IV (i would think that he could use a UTM here as well, as long as it is meters)  The feet can be specified after the point cloud is created to get it converted correcty.

Attached is a screen shot of the point cloud i generated.  I could send the point cloud data, but its almost 600 MB.

[AllenJessup]

I opened your ADF Surface drawing, erased the Surface, Created a new one and imported the ADF using LL83 as an input CS.

That resulted in a quadrangle aprox. 380000 feet on a side.

[AllenJessup]

I did the same but created a Surface. LL83 looks good as an Input CS.

[Anonymous]

Oh man....how did you get it to scale properly! And can you confirm what you mean by input and out for the CS's?

And can you please list the following:

• CS of the drawing file and meters/ft
• CS of point cloud meters/ft

I need to apply this to the 1/3 arc files so i appreciate the thought but I need to get the scaling right. What about post the file you created? Maybe I can just import the point cloud thru that .dwg and it might work?

Thanks a lot.

[Anonymous]

here's my drawing with the point cloud data not attached

it scaled the same as allens

[Anonymous]

here was my process

use mapcsassign and set drawing to CA83-VF

in toolspace

right click point cloud -> Create point cloud..

on first page, name point cloud.

on second page, under source data select esri ADF, hit the plus sign and add the w001001.adf file.

click where is says coordinate system <none>, change that to LL83

Under new point cloud database, hit the three dots and change that to CA83-V  (this is the metric one,NO Feet based CS)(this is where i screwed up last time)

Then hit finish and wait.  

[Anonymous]

Many thanks to both of you guys, the scaling is coming in properly now. Only issue is now the coordinate system doesn't match the USGS locations (-119, 35) and are x,y decimals. Is there a way to convert it back to match the USGS without affecting the scaling?

Thanks.

[AllenJessup]

Not really. You've gone from a system where 1° = 1 drawing unit to a system where 1' = 1 drawing unit. About 380000 times the size. There is a function in Map that will allow you to track different coordinate systems. I don't remember it at the moment and will have to wait a while until the program is finished it's current task so I can look it up.

This is a link to the coordinate tracker help https://knowledge.autodesk.com/support/autocad-map-3d/learn-explore/caas/CloudHelp/cloudhelp/2016/EN...

But I was looking for the command line equivalent. When I find it I'll post it.

Edit: One of them is MAPTRACKS

[Anonymous]

not sure i understand the question.  you were essentially in the original lat/long coordinates when you were getting the 1x1 block.  it is now scaled up to a plane coordinate system in feet.  Why do you need to go back to lat/long?

[Anonymous]

I have other information that i need to import that is located within shape files based on lat/long. Maybe this isn't possible or I need to adjust the shape file somehow to the same coordinate system?

Another thought i had was bringing in the 1x1 grid in lat long, with the other components I need, then block the surface with the components. After that I can bring in the correctly scaled point cloud boundary then insert the blocked surface and scale the components accordingly. That make sense?

Also, I forgot to confirm if you are starting with an imperial or metric .dwt.

Thanks

[AllenJessup]

I started with your drawing but it should be an imperial dwt since that's your target system.

For the entities in the shape file. I'd bring them in to a drawing with the native coordinate system set. The use a Map Query to bring them in to the target system. This works well for non-Civil3D entities but you can't use it on Civil 3D objects.

[Anonymous]

as long as you use mapimport to bring the shapefiles in and assign them the correct input coordinate, CAD will take care of the transformation and should place them in the drawing appropriately.