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.

[Pointdump]

TCG,

I haven't used ADF files yet. Where did you get them? How did you import them into your drawing? What Geographic Coordinate System is the data in? (Metadata: LL83, LL84, etc)

Dave

[Anonymous]

Dave,

I downloaded the .adf files from a usgs site, and the CS is NAD 83. I created a point cloud by the ESRI ADF option and then created a surface from that point cloud. The elevations or Z data are accurate, and even the coordinates when listed match up within the 1x1 grid tile. I just need the horizontal or X,Y distances to match real world. If I draw a 5ft line it extends 4ft out of my surface boundary, which is obviously way off. 

I've attached the drawing to better help depict the issue. The surface displays contours and coordinates correctly within the 1x1 grid tile, but I need the grid tile and coordinates in the drawing to be scaled accurately to real world situations, not be 1'x'1.

Thanks for the response 

[AllenJessup]

Dave, ADF files can be brought in with AeccCreateSurfaceGridFromDEM (Create Surface from DEM). It's and ESRI Binary Grid file.

[Anonymous]

Allen,

Seems you have some experience with .adf files, do you happen to know of a fix for this issue? I need the 1x1 grid to not be 1ft x 1ft but to be 1deg x 1 deg and have the coordinates line up correctly. I read this on the USGS site that referred to the scaling of their grids:

At 38 degrees North latitude, one degree of latitude equals approximately 364,000 ft (69 miles), one minute equals 6068 ft (1.15 miles), one-second equals 101 ft; one-degree of longitude equals 288,200 ft (54.6 miles), one minute equals 4800 ft (0.91 mile), and one second equals 80 ft.

I've been messing with the units and coordinate systems but cant seem to make the lat/long distances represent these measurements. Everything is set at 1ft scaling. So from 39 degrees to 38 degrees, or -119 to -118 is only 1 foot. Any help is very appreciated. 

[AllenJessup]

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@Anonymous wrote:

Seems you have some experience with .adf files, do you happen to know of a fix for this issue?

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Hi Teacadguy,

Unfortunately I don't. I did a quick of Civil 3D help to find out what I was dealing with. I was going to download a file from the USGS to see if I could do anything with it but it's way too big to justify downloading at work. We have an old network that slows down very quickly.

What I'm thinking is there should be a better way to convert from Metric to Imperial but haven't come up with one yet.

Dave is the real wiz at this and hopefully he gets time to do some research.

[Anonymous]

Thanks for the response Allen.

It doesn't seem like the conversion from metric to imperial is the issue, since that scale factor is .3048 (meters to foot). There's a very good possibility I'm wrong but I believe it has something to do with the coordinate system settings. I need the 1 degree distance in the drawing to match the actual real world distances. I did a sanity check on Google earth to confirm the distances that the USGS listed and they are correct.

Does anyone know how to apply scale factors to a coordinate system so they scale out at the measurements listed above by the USGS?

Thanks

[AllenJessup]

Check out THIS link for how to bring in a metric DEM (ADF) file. It looks like the process has quite a few steps and you may have missed or not known of one.

[Anonymous]

Thanks for the suggestion but that is the actual page I used to convert the file from meters to feet. Regardless of creating a surface from a dem, creating a surface then in the definitions adding the dem, or creating a point cloud then adding that to a surface, all of them only come in with the grid defined by 1ft by 1ft. The metric comes in as 1x1 meter grid then once converted to feet its a 1x1 foot grid. 

There has to be some way to adjust the coordinate system so it matches the USGS distances no?

Thanks

[Anonymous]

I'm working through the same problem now.  I've done it before its too long ago to remember exactly how i did it.  your point cloud is in lat/long.  USGS DEM's are 1 degree x 1 degree which is why it is one unit wide in CAD.  If you property the point cloud, it probably says no coordinate system.  USGS DEMS are in LL84.  I think the last run i did i typed in LL83 which may have screwed it up.  I am currently reruning it, but it does take quite awhile.  Once the point cloud knows which CS its supposed to be one, then you can set the drawing CS and it will adjust accordingly.  I'm just stuck on getting the CS set in the point cloud.

[Anonymous]

Hey Mderr,

Thanks for the response, glad I'm not the only one who experienced this.

You think it could be something within the feature settings of point clouds, accessed through the toolspace settings tab? I just browsed thru there and am trying to start the process again with changing the lat/long options in the feature settings. Question though, when I property the point cloud it doesnt list an option for a CS? Where are you accessing that info?

Thanks

[Anonymous]

I really wish i had documented it better.  I did two files probably 4 or 5 years ago and have been using them without trouble ever since.  My last run failed as well.  This time i'm trying to set the point cloud database to stateplane in meters MT83 instead of MT83F.  This is how my old ones that work are setup.  I set the coordinate of the .adf file to LL83.   

Attached is a screenshot of the point cloud properties for the one that works.  if this run doesn't work, i may set everything in the drawing to MT83 before running it.  It's kinda coming back to me now.  Run in meters first.  Then switch the drawing coordinates after the point cloud has processed.

I'll let you know if i figure it out.

[Anonymous]

Ok great, thanks.

I've made sure to start a new metric drawing before loading the point cloud each time, I think you may be right thought with it being something related to the CS setup. I've tried Lat/Long and state planes and they all come in to 1x1 grids, nothing is ever at the correct scale. But it doesnt seem to be the cloud itself it is the parameters of the CS in the drawing. I can't do anything with the surface it creates if it is at such a minute scale compared to real world dimensions.

Really appreciate the help.

Thanks.

[AllenJessup]

Can you share the Metadata for the file?

[Anonymous]

Okay great, thanks.

I've made sure to start a new metric drawing before loading the point cloud each time, I think you may be right thought with it being something related to the CS setup. I've tried Lat/Long and state planes and they all come in to 1x1 grids, nothing is ever at the correct scale. But it doesnt seem to be the cloud itself it is the parameters of the CS in the drawing. I can't do anything with the surface it creates if it is at such a minute scale compared to real world dimensions.

Really appreciate the help.

Thanks.

[Anonymous]

the whole file can be downloaded from the national map elevation data in ARCGrid Format

Attached are the meta files for the adf.

I think autodesk has pretty much given up on map as most of the answers nowadays says to use infraworks (at an additional cost of course)

[Anonymous]

Allen, attached is a zip with the provided metadata from USGS. They are in .adf format.

Let me know if you find a fix.

Thanks.

[Anonymous]

Success for me.  There has to be a silent error in converting from LL83 to state plane feet.  Setting the database to state plane meters when creating the database worked for me.

I attached a screenshot of the create point cloud screen.  I changed to meters in the three dots highlighted in blue.  didn't seem to care that my drawing is still in feet.

Hopefully this helps.

[AllenJessup]

Can you give me a link to the metadata on the USGS site? I'm looking to read what they say about the original CS. I tried just selecting a UTM 14 Metric and got a square 3.28 feet on a side.

[Anonymous]

Allen,

I've attached the full zip that USGS provides including the read me pdf about their CS.

Thanks.