DWG topographic maps

[axk5889]

Does anyone know where you can find topographic maps of different wilderness areas/national parks that are converted to DWG files? I guess there was a website called topodepot.com which used to sell them, but it's no longer up and running. Any ideas?

[axk5889]

Mariposa County, California

[ChicagoLooper]

OK, great. Enter NEW on command line. Open an imperial template, not metric. It should have 'imperial' somewhere within the template's name and have dwt as an extension. Name and save this drawing, you don't want to over write the existing template.

On command line type in MAPCSASSIGN. In search box enter CA83IIIF. It will have an EPSG code of 2227. Select this coordinate system and click assign button.

Use MAPIMPORT command and import the contour shapefile with the very important object data. If you have an Autodesk 360 account (it's free to get one) you may turn on Bing Hybrid maps.

[axk5889]

That worked! How did you find out that that was the correct code for this county? Is there way for me to look this up for different projects?

And the last piece of this is that I'm trying to combine a few of these TNM USGS maps because the area I need spans a few different map segments. Do you know of a simple way to combine a few maps or is there a way to manually select a specific area from the USGS site? or would I need to connect each individual contour line from the adjacent map segments?

Thanks,

Alex

[ChicagoLooper]

Wow! So you need more than one quadrangle (USGS map tile) to cover your area? Your project sounds ambitious. Good for you!

For Geopdf's, yes there are other maps in smaller scales that cover a wider area, but for vector data, like shapefiles, no. This means you'll need to download more than one shapefile to cover your area. USGS only offers shapefile and gdb data in 7.5x7.5 series quadrangles. For geopdf's, though, you can see the different coverage areas based on the map scale in Image 1 below.  The smallest map Tile is a 7.5x7.5 minute quadrangle. A 15-minute map is four quads, 2 columns by 2 rows and 1-degree map is 16 quads, 4 columns by 4 rows. 

1-Raster maps are available in different scales.

There are various ways to ascertain a coordinate system. Since coordinate systems in the US are based on counties, start with the county to find your coordsys. As a bonus, you can even search a specific county's website, where you can find useful downloadable data, e.g. parcel shapefiles, georeferenced imagery. The data available varies widely from county-to-county. Some have free downloads, some don't. Some are technical-rich and have free downloads whiles others are antiquated with data only available 'by request' which may incur a fee.

If you only need to search or lookup data, many counties have user-friendly ONLINE MAP VIEWERS  where you can zoom and pan around to view county data such as parcels, admin boundaries, land use, flood zones, historical imagery, etc., etc. The viewable data varies widely from county-to-county. Some even allow you to download, i.e. parcel data in csv format or aerial photo imagery as pdf or in raster format.

Online viewers are typically easy to find by a search engine while others are buried and only found by accident or when your search contain certain 'key words.' 

You can use this website by >>AVENZA<<  to look up a coordinate system. In the upper right section of the map, search using County name and all counties in the US that match will highlight in red. Hover your cursor within the red boundary and when it turns green a popup will appear with the appropriate coordinate zone. In your example, there's only one county named Mariposa. See Image 2 below. Try doing a search on 'Lake' and see what happens.

2-Try using Avenza when searching for a US coordinate system.

Avenza Notes:

• Spelling counts, capitalization doesn't.
• County names can get tricky, e.g. St. Louis, St Louis, Saint Louis, so trial-n-error might be necessary.
• Louisiana calls their counties a Parish.
• Most States have more than one zone, e.g. E & W or N, S & Central. Some states have just one zone.
• You don't necessarily have to type in and search a county. You can simply use your cursor to view the popup.
• Both Minnesota and Wisconsin have coordinate systems for each county in addition to the typical 'State Plane Zone' and Avenza only has the SPCS, not the county zones. To see what the county zones look like, you may use MAPCSASSIGN command and search 'Minnesota.' Scroll through the results and you'll see both Minn SPCS as well as the various 'county' coordsys.  

[axk5889]

Thanks! That's a great help.

[axk5889]

Hi Dave,

I'm going through this process again for a new project and I've hit a roadblock. When I'm defining the current query, the category with the elevation data -- ContourEle -- doesn't appear to be in the property alteration expression dialog. Do you have any idea what might be causing this?

[Pointdump]

Hi Alex,
Maybe your latest shapefile doesn't have elevation data. Can you post your shapefile? Zip everything together: DBF, PRJ, SHP, and SHX.
Dave

[axk5889]

I've attached it here. I think it has the elevation data. It says there is a category for it. When I used the MAPIMPORT command I just uploaded the .shp. So maybe I need to upload more of this data for it to work?

[Pointdump]

Alex,
Thanks for posting your shapefile.
Yup, it's got elevations. In Elev_Contour.shp the OD(Object Data) name is "ContourEle".
Dave

[axk5889]

Thanks, Dave. I tried that again and it worked. My elevation data seems a bit off though. It looks correct from the top view, but the side and 3D views don't seem right. The screenshots are of the top and left views. Maybe this is a scale issue? Any ideas?

  

[Pointdump]

Alex,
Dunno. That's not the same shapefile you posted. Try this: Select all your contours, right-click, and select "Object Viewer".
Dave

[axk5889]

I tried objectviewer and no luck unfortunately. So here's the same shapefile from before after going through the process of attaching the elevation data. Do you see how there seems to be a scale issue in 3D? Any ideas?

Thanks for the help,

Alex

[Alfred.NESWADBA]

Hi,

>> So here's the same shapefile

This is not a SHP-file, it's a DWG-file.

>> Do you see how there seems to be a scale issue in 3D?

Why is it a scale issue? What is different to your expectation?

This is what I see, polylines, having ObjectData attached and having an elevation set to the same value as the ObjectData's field "ContourEle"

- alfred -

[axk5889]

Thanks, Alfred.

So I didn’t explain that well. That file is a .dwg with the shape file data attached as object data. 

The 3D elevation data should look somewhat similar to the attached screenshot. But for some reason, if you go into the file and view it in 3D the contours are sort of stacked and not displaying like terrain normally should. And I’m not really sure why?

[ChicagoLooper]

You have topographic contours in shapefile format with elevation data. You want to convert the contours from ESRI linework to AutoCAD polylines. This video shows how to convert the shapefile vectors to plain vanilla polylines.The video also demonstrates how to create object data (OD) from the shapefile's database file (dbf). Using the Map3D toolset, the OD will then be used in a specialized Query known as 'Alter Properties' to raise the polylines to their proper elevation. The video concludes with a 3D orbit of the raised contours.

To watch the video click >>HERE<<.

NOTES: 

• At 30 sec into the video, Object Data is ‘created’ during the MapImport procedure. It is critical to create OD because without it, you won’t be able to raise the contours to their respective elevations. 
• You will need to make two dwg files: the first one to perform MapImport and the second to run your query. You cannot complete the operation with only one dwg file. 
• The contours were downloaded from USGS TNM download site. The Quad’s name is Phantom Ranch, AZ and covers part of the Grand Canyon. The Quad abuts Tusayan East on the north. 

[Pointdump]

Alex,
"...if you go into the file and view it in 3D the contours are sort of stacked and not displaying like terrain normally should."
You didn't assign a coordinate system, so when you brought the LL83 shapefile into your drawing AutoCAD assumed the units were feet. They were really degrees, which is why your drawing "bunches up".
Dave

[axk5889]

I think we're on the right track here, but it still isn't quite working. I had MAPCASSIGNED LL83 to the initial file when importing the shapefile data, but not when I attached that to a new file in the Map Explorer. So I tried it again, assigning the coordinates as LL83 in both files and it's still 'bunching'. Do I need to change the units or something too?

[ChicagoLooper]

When you perform MAPIMPORT, Assign AZ83-CF to your modelspace. Map3D will understand the native coordinate system of the Topographic shapefile you are importing. He understands because he is ‘reading’ the shapefile’s projection file, AKA the prj.  The MapImport command is smart and powerful and will automatically will convert from the map’s native lat/long CS to your modelspace assignment of Arizona State Plane. Assigning the same coordinate to modelspace as the shapefile is NOT mandatory. 

Converting from Lat/Long degrees to State Plane feet during MapImport allows you to abandon degrees and work exclusively in units of feet from this point forward. 

Next, when you open a new or another drawing to perform your query, assign AZ83-CF to modelspace. This ensures the line work will plop down in the correct geospatial position once the query is executed. Assigning AZ83-CF (or any projected CS for that matter) will also allow you to turn on Bing maps.

BTW, Bing maps are not accessible when you don’t assign a ‘projected’ coordinate system. IOW if you assign a ‘geographic’ coordinate system such as LL84 or LL83, both of which use units of degrees, you won’t be able to turn on Bing. Yes, Bing only likes projected CS’s. 

[Pointdump]

Alex,
I can't add anything to the excellent advice from @ChicagoLooper. Watch his video in Message #35.
Dave

[axk5889]

Yes, that's a great help from both of you. Thank you so much!