Contrary to popular belief, the coordinate system of the shapefile does NOT have to be the same as the coordinate system assigned to modelspace. It is entirely possible to execute the MAPIMPORT command on a shapefiles with a geographic projection in degrees, such as WGS84 using lat/long, while modelspace is assigned a State Plane coordinate system. Do not make the mistake of thinking your modelspace MUST be assigned WGS84 lat/long when you want to import a shapefile. This is a mainstay of Map 3D, where coordinate transformation occurs on the fly.
To test your work flow when using the MAPIMPORT command try this:
- Using Map 3D, open an out of the box, clean, fresh, new unencumbered imperial template. Since you mentioned parcels, easements and centerlines downloaded from the County, I am assuming you are drawing a site in the US and you are drawing in feet and not meters.
- Assign a State Plane to this new drawing making sure you use the appropriate state plane zone.
- Execute the MAPIMPORT command and import the shapefile you downloaded from the County.
- Zoom Extents then turn on Bing imagery.
- Measure some parcels or easements or other imported entities using the default dimension style in the template. Use the Standard dim style, not a customize one.
Do the dimensions look OK?
Chicagolooper
With the limited info you have provided (you should upload the dwg file AND the shapefile) it sounds like your dimension style. By uploading your dwg and the shapefile, a better explanation, and more comprehensible answer, can be posted without trying to argue the correctness of the solution.
If everything matches fine and dandy, then the drawing scale is not off. What is off is the DIMSTYLE or possibly the drawing units, where the drawing units of inches is being read as the distance and that distance is being given units of feet instead of inches. For example, the distance of 72-feet is being read as 864-inches. Why? Because 864" equals 72'. Unfortunately, your dimension style is not displaying the inches sign, or (") but displaying the (') sign instead.
If it did display the inches sign then the distance would be correct at 864-inches and measuring distance in purely inches is not considered a best practice. It should be 72'-0". Check both your dimstyle and your drawing units. Your dimstyle should be using units of feet, not feet and inches, not architectural, just feet. For your drawing units, leave it at the default, which is feet in Map 3D. Don't get fancy and impose your own dimstyle on top of M3D.
Chicagolooper
Accepted solution
Your modelspace is using architectural units which means you are drawing in feet and inches. Your engineering line work, however, is using units of feet. By engineering drawing I'm referring to entities such as road centerlines, easements, subsurface infrastructure, utilities, etc.
The default units for Map 3D, as well as Civil 3D is FEET and NOT feet-and-inches like an architectural drawing. You are mixing the two types of drawings and that's a NO-NO. When you use MAPIMPORT command to import a shapefile (as opposed to using an FDO connection to bring in the shapefile), the shapefile is expecting the drawing units to be in FEET. Sadly, that expectation is not being met.
It is not that your dwg, or some variable within your dwg, that is making the shapefile 1/12th too small, it is your drawing that is 12X too big for a M3D/C3D drawing! Don't get me wrong, it's perfect for an architectural dwg, but it's not using the appropriate 'dwgunits' for a C3D/M3D drawing and it ends up too big. Since you are using a shapefile in your drawing, you must ditch the feet-and-inches and make your current drawing conform to FEET.
Other issues in your drawing:
- It is not correctly georeferenced to Iowa State Plane, North Zone, US-Feet. (MAPCSASSIGN on command line then search for IA83 in search area, then choose IA83-NF and click ASSIGN.)
- When you use MAPIMPORT command to import a shapefile, the shapefile is expecting the dwg units to be in FEET and not in feet-and-inches.
- Go back to the original survey (or engineering drawing). It is correctly referenced and your shapefile, when imported properly, will be positioned correctly against the AutoCAD line work. If you are manually moving the imported shapefile to be on top of the road line work then you are doing the entire operation incorrectly.
At his point, you need to forget about your 20 years experience and treat Map 3D like a new program. The experience you're carrying is unneeded baggage that is impairing your ability to resolve the issues in your Map 3D drawing. Forget your line work too, at least for now. You need to start from a plain, empty, clean, fresh imperial template to bring in the shapefile. Once it's brought in you can measure distances all you want. Then bring in your road line work, not before.
The reason you want to bring in the shapefile first is to see it against Bing imagery, to see how it relates to other geospatial entities such as parcels and coordinate geometry such as lat/longs from a surveyor, and to see how it plays out against existing geospatially accurate elevation points. If your road line work and easements are not geospatially accurate, then it may as well be in Disneyland instead of Iowa. As long as the easement distances are correct and the road widths are accurate, who cares if you're in California or Iowa?
Chicagolooper
Huh? SHX file?
Sounds like you need a crash course in feature data objects.
A shapefile consists of four (4) components:
- SHP
- DBF
- PRJ
- SHX
SHP: This component is a vector. A shapefile may contain Lines. Or a shapefile may contain Polygons. Or Points. Furthermore a line, polygon, or point is considered a feature class and the shapefile format can only contain one feature class. Therefore, a point shapefile, polygon shapefile, OR a line shapefile, NOT a combination. Never ever. The feature class (or vector) is 'clickable' so you may select a vector in modelspace using your mouse.
<<If you see multiple feature classes in a single file, then it's not a shapefile, it's a Geodatabase (Gdb). A Gdb can contain multiple feature slasses. AutoCAD's SDF format is akin to a geodatabase because it can either contain a combination of feature classes or just a single class.>>
DBF: This component is the Database File. You can view the database of a connected shapefile by opening the Table View. The table has rows and columns of neatly organized data and looks like a spreadsheet. You can use data in the rows and columns to make labels in your map. Data organization also allows you to isolate groups of vectors according to specific criteria you decide to use, such as all parcels greater than 10,000 square feet or all trees designated by the Tree Guy to be chopped down for safety reasons.
PRJ: This component is the Projection file. When modelspace has a properly assigned coordinate system, the shapefile's Prj file makes it land in the right spot, at the right scale, and with the right orientation. If your assigned CS is bad, you'll have issue georef'ing your shapefile. If the shapefile's author gave the shapefile the wrong Prj, his error will adversely affect your linework when you build your map.
SHX: This component is an Index. It's responsible to LINK the Dbf with the SHP (or vectors). If you click on a vector in modelspace, a row in the Dbf Table will be highlighted. Also, when you highlight a row in the Dbf Table with your mouse, the vector in modelspace will glow yellow indicating its been selected in the Table. You could say the Shx file allows you to go forward and backwards--from clicking in modelspace to Table highlighting OR from Table row selection to yellow glow in modelspace.
So.....your question is when you bring in a SHX?
What does bring in my SHX mean? Surely you don't mean you're bringing in something that allow you to goes forward and backwards, do you? Explain. Add screenshots or upload a video.
If your vectors are not landing in the right spot, then you didn't assign the correct CS to modelspace. Assigning an appropriate CS can be tricky, very tricky, especially if you rely on a method commonly used by others who don't understand how to do it in the first place!
It might also mean you don't understand the shapefile's native CS. Understanding the CS given to the shapefile by the original author can be tricky too and that trickiness makes the insertion process unnecessarily complicated.
Chicagolooper