Ii have Carlson 2011 w/ AutoCad 2011. I would like to download a pdf file from my local county GIS mapping site and import the contour layer into a cad file and use them to design a grading plan. I am new to Carlson and AutoCad. Just looking for someone to point me in the right direction. I would also appreciate advice on how to import and ortho image into the cad file and sync it with my assumed coordinate system at a street centerline intersection. Thanks in advance.
this is a joke, right?
command you want is "image". Make a PNG or GIF or TIFF of the PDF and insert the image, use align (in 2d) to get it behind your linework (might need "draworder" to put it behind). When you get it where you want it, you can create new linework over it.
I wish that I was so perfect that I could declare someone's honest, well stated question "a joke".
Dennis,
Being 98% retired, I'm running legacy AutoCAD, namely Release 14, but a good deal of the following will probably apply on later releases.
By bringing the image in first, and adding linework later, it's possible to avoid using the draw-order command to bring linework to the front. That command works, but generally has to be re-done each time the drawing is opened.
I've been using .jpg images. I usually insert them starting with a scale factor of 500 and re-scaling after that. A scale factor of 1 brings the image in with one side of it equal to one drawing unit, too small to do much with. The insertion point that you input corresponds to the lower left corner of the image. The first insertion point has to be estimated. After adjusting the scaling and rotation, the insertion point then needs to be adjusted if you have a coordinate base that you want to match.
Of course you need at least two objects visible on the aerial, with a known distance and azimuth between them, to get the scaling and rotation correct. It would be possible to use something like a record bearing and distance between a couple of fence corners, etc., but far better to pick out two well-defined objects on the aerial and tie them in the field.
In setting the scaling and rotation, I zoom in to each of the visible items and set a point object at the point I'm using, such as a building corner, power pole, etc. Then I zoom out till I can see both points, set osnap to "node", snap and measure a distance and azimuth between them, and use that data to correct the initial scale and orientation.
By doing two or three successive scaling/rotation adjustments, it's not too hard to get the CAD distance and azimuth between the control objects to agree with the known values within less than a foot. But no aerial is perfect, and there is likely to be some distortion everywhere else.
It's possible to input a rotation angle for the image in the insertion menu. However, the menu treats any angle that you input as counterclockwise, regardless of the Units settings in the rest of the drawing.
As stated, this is all based on R14. E-mail me for more information if you like. jvcls at aol dot com.
Using GIS contours to design something does not sound like a good idea at all. The contours might not be that accurate in the first place; they might not be correctly positioned horizontally with respect to objects on the ground; and retracing the datum on the ground would be an uncertain proposition at best.
GIS contours might be OK for a "concept" drawing, but anything that's actually going to be built should be based on field topo. Otherwise there could be serious construction problems and big extra costs.
really? you think creating a grading plan from topography on a GIS site is not a joke? the guy says he is a PLS and a PE...he should know better.
All the cartographic drafting techs in America are sadly shaking their heads. I suppose ypu feel that this proceedure is OK, but my initial reaction is that the first thing that you need to do is double the amount of Errors & Omissions insurance that you carry.
GIS info is great for planning only. Take it one step beyond that and you are asking for massive litigation. It's your bank account, it's your house, it's your seal, so do what you wnat to do, but don't get pizzed when someone says, "I told you so!!".
No, not a joke. Thank you to those that took the question seriously. I have always been of the opinion that the participants in this forum were very open to sharing their knowledge with those wanting to learn. The grading plan is just a learning excercise for myself and is not a client work product. I figured it was easier to import contours and work off of those than the effort required to develop a contour map from a field topo survey for my intended purpose.
any job doing is worth doing right..you will learn much more using actual field data than some GIS contours. Creating surfaces is very important in your design. It is my opinion that I am doing someone a disservice by helping them to learn how to use data inappropriately. Now had you came on and said, I want to check my field data against the GIS, I would of been more than happy to help.
I don't think we know enough to judge him. You do. We disagree.
New year coming up - PEACE.
I would assume this is for preliminary work or a joke.
1. How was the PDF created? Is it a scan of a map or was it created from a program? If the latter, there are several programs that will convert the PDF to DWG.
2. Convert the PDF to TIF. I like to use two-color tiffs so the transparency works best. I typically use the ALIGN function and two points to bring it in. Typically I use this process to bring in recorded plans, then I input the plans on top of the images. Transposed quadrants really show up. Plus, I can leave the record plan behind the CAD property lines and my working plans are completed without much drafting.
3. Why would you leave it in an assumed coordinate system? Most GIS data will be made available on SPCS, so why not move your data to the image? I will do this for a preliminary working plan so I can get out with the GPS and have some fairly close initial coordinates. Great for reconnaissance but it is important to keep track of the preliminary vs. the final coordinates.
Beware of GIS data. Get it surveyed. Also look into the other GIS data available. Most states have DTM models available (with metadata). This is typically how Google Earth staff will create the 3-d effect of the terrain. I typically use DTMs to contour areas outside of locus, just to be able to see what the rest of the world looks like. Document sources and quality.
In creating design contours, you will have to be able to visualize the 3D shape of the existing surface and then of the surface you are designing. No one is born with that ability; you have to practice. There's no such thing as a short-cut method of practicing that or any other skill. It takes time. Happily, in this case you don't have a project deadline.
As an aid to learning to visualize surfaces, it would be very helpful to create the existing contours from scratch, not via software but with pencil and paper. Plot out the field shots and elevations to scale on a large sheet of paper, draw lines to create the net, interpolate to set integral-foot elevations along the lines, and draw the contours. You'll then see for yourself that existing contours consist of something like 25% field data and 75% processing.
You must have some old jobs you could import for the exercise. Carlson is very good about working with other formats.
For a learning exercise, your technique might not be the most practical or the easiest to implement. Creating a set of contours from a PDF is difficult and inaccurate, probably not something you'd want to do in a real-life scenario.
I've taken the liberty of creating some sample files that might be a more realistic working scenario. Included is a aerial jpg, dxf of contours, and an ascii grid file of elevations.
You can download the sample data here:
By the way, if you do still want to convert a raster format such as PDF or JPG to a CAD format, I might suggest a open source raster to vector conversion program, my favorite is POTRACE:
http://potrace.sourceforge.net/
Once you convert the image to the required input format (PBM) you can export the file directly to DXF, it has a number of smoothing and pre-processing options.
If the PDF is vector based you may be able to find a plugin for photoshop or illustrator and work with the contents without rasterizing it.. but I've never gone through that route.
> I wish that I was so perfect that I could declare someone's honest, well stated question "a joke".
well said :good: :good:
> Ii have Carlson 2011 w/ AutoCad 2011. I would like to download a pdf file from my local county GIS mapping site and import the contour layer into a cad file and use them to design a grading plan. I am new to Carlson and AutoCad. Just looking for someone to point me in the right direction. I would also appreciate advice on how to import and ortho image into the cad file and sync it with my assumed coordinate system at a street centerline intersection. Thanks in advance.
Hi Dennis, Im also new to Carlson and is still currently familiarizing with the software. I think the Carlson Take-Off module in Carlson Survey may solve your PDF import queries. Please refer to the below videos for better guidance;
More helpful tutorial videos are available on the Carlson website www.carlsonsw.com
Have a Happy New Year!
Jef
Additional info:
To convert a PDF to a graphic image, PDF995 and Omniformat (free, adware) are a good combination.
The real fun begins when you use GRASS-GIS plugins in QGIS to make a DEM from a paper contour map. Still working on that one for deer season next year.
I dont think I was judging him, I just thought it was a joke someone was playing on the board. I am sure I wasnt the only one who thought that, a more likely scenerio though is that he is a government employee trying to either do a job in the office that really needs field work or he is learning how to use the software so he can moonlight or help a friend. Either way, I am still not judging him. I just thought stressing the fact that these contours would be worthless was the best advice I could give.
