California Surveyors Forums

Good Afternoon all,

As boundary surveyors, it is common for us to use a compass rule adjustment between found monuments to "adjust the line".

I have an old windows 98 computer with "pac-soft" dos cogo software and it is almost dead (ive brought it back to life a couple times). Im looking for other options to adjust my data, either new software or other.
If I remember correctly, the compass rule adjusts angles and distances concurrently.

During one of the lectures for my LS Prep Class (a few years ago), our instructor had mentioned the "Align" command in AutoCAD. I do not know much about this command and cannot find much information when googling it. I do use this when overlaying images/etc
If im not mistaken, this adjusts/scales the distances and not angles.

Please correct me if my thinking is off for either method...

Is the "Align" command something that is accepted by surveyors in liue of the compass rule adjustment? What software is the most common for the compass rule? When do others use the align command?

Thanks,
Drexyl

My understanding is that the Align command is a move, scale and rotate routine. If you "Align" an AutoCAD entity (polyline or series of lines) then it would preserve interior angles and scale the distances proportionately to fit start and finish points (mine offers you an option to scale or not).

This is consistent with my understanding of a Grant Boundary Adjustment. It seems very similar to a Compass or Bowditch Rule Adjustment but I don't use these terms much. I use this "Align" command frequently, several times each day for different applications, scaling and rotating symbols, aerial imagery, cogo points, etc....

Thank you very much David.
I appreciate the feedback.

I'd also note that the align command can be used without performing a scale, so it will just translate and rotate if that's your preference. One difference is that it will translate the points based on the first selected source and target pair, so you'll see all your residual on the second source and target pair.

It also tends to give odd results from time to time, particularly when dealing with 3D linework, so having lots of common check points to verify it worked correctly is critical.

I quit using the compass rule adjustment about 25 years ago. I do not recall specifically as to why I quit. I suspect it was the about the same time my last HP41CX died (still sits the drawer next to me) and I was transitioning to using ACAD for more than mapping.

It was about this time I started using the grant boundary method exclusively to establish senior lines with missing monuments. The main reason was the ease of documenting and mapping the process with a citation. It is easy to map and check the coefficient between two found monuments and verify the record interior angles.

The technical process is to calculate the record figure, divide the measured distance into the record distance to determine the coefficient. Scale the record figure in ACAD using the coefficient, done. I map a detail showing the process/measurements etc. Credit where credit is due, I was educated on using this process for land boundaries (for land other than public lands) by Marilyn Brooks, CA PLS 5831.

I am not sure I could do it anymore, but I recall the compass rule adjustment being super easy to do by hand. Google “balancing latitude and departure form”. I used to teach it and recall being able to do the adjustment using a form in about the same amount of time as executing a program.

Good luck.

DWoolley

If we are going to give credit to our boundary determination mentors, I nominate mine: Jon Edward Howard, LS 3342. I learned much from this man, but retaining the integrity of the interior record angles was paramount. Being a rookie at LS 5684, I absorbed as much as I could from Jon and others. I miss those days. The best and most representative example of ownership of our products that there is in our profession.

SPMPLS wrote:The best and most representative example of ownership of our products that there is in our profession.

What are you saying? Please elaborate

David Kendall wrote:

SPMPLS wrote:The best and most representative example of ownership of our products that there is in our profession.

What are you saying? Please elaborate

Simply that our boundary determination products are at the core of why we exist as a profession. We own them for life and beyond from the moment we affix our seal and signature. They impact or define the thing that is the most valuable and protected asset that people possess.

I still use the compass adjustment method, Carlson software has a nice routine and provides a good report. It also has the grant line adjustment method available.

Armand Marois

Dave,

In our office we almost always do the same, I.E. GBA (aka Scale command) to maintain interior angles along a senior boundary between found points/positions, and I feel that it is right and proper, however while explaning this to one of of our LSITs, they asked why we were holding angles over distances when it is was CA law that distances have priority over angles.

After thinking if over I told him well, because I was taught that way, and I have found that most guys measured the angles better up to the adoption of better technology in the 1970's -1990's (depending on surveyor) or so and this follows in their footsteps better. I have been searching for a more "backed up" reason and was wondering if you had a better rationale?

Mikey Mueller, PLS
Sonoma County

PS Minor digression, at this point the difference between angle over distance seems moot (except for least squares adjustments), as blunders and incompetence blow the precisions concerns out of the water. IE Whenever we attempt to retrace another surveyor's modern lines, there doesn't seem to be systemic angle or distance errors.

Mikey:

The Grant Boundaries method, described in the outdate 1973 Manual, does consider angles. The angular delta of the “connecting line” between two monuments is a rotation of the figure. See Figure 73 on page 143 of the 1973 Manual. From the Manual:

“Both angular and linear corrections are made in the direction needed to reduce the falling of the trial lines laid down according to record”.

In the alternative to a Grant Boundaries method, the angular delta would be distributed throughout the figure by balancing/distributing of the angle delta between the established corners. This would be essentially a compass rule adjustment.

In my opinion, each are equally acceptable methods and although different, each accounts for deltas in angle and distance.

DWoolley

Mike Mueller wrote:Dave,

In our office we almost always do the same, I.E. GBA (aka Scale command) to maintain interior angles along a senior boundary between found points/positions, and I feel that it is right and proper, however while explaning this to one of of our LSITs, they asked why we were holding angles over distances when it is was CA law that distances have priority over angles.

After thinking if over I told him well, because I was taught that way, and I have found that most guys measured the angles better up to the adoption of better technology in the 1970's -1990's (depending on surveyor) or so and this follows in their footsteps better. I have been searching for a more "backed up" reason and was wondering if you had a better rationale?

Mikey Mueller, PLS
Sonoma County

Mike, thank you for asking this. I've wondered the same.