Hello,
I do not understand how to use my SMI software to transform coordinates. I have created a fictional job to illustrate my predicament. I have created points in my SMI card for two centerline PCPs, and four property corners. These are calculated points based on a plat. When I arrive at the job I set a nail across the street from the property, and occupy it.
Calculated Points:
Point Northing Easting Description
100 5000.0000 5000.0000 PCP
101 5000.0000 4400.0000 PCP
102 5025.0000 4900.0000 PROPERTY CORNER
103 5025.0000 4840.0000 PROPERTY CORNER
104 5105.0000 4840.0000 PROPERTY CORNER
105 5105.0000 4900.0000 PROPERTY CORNER
I call the nail point number 2, and give it coordinates of 10000.0000 northing, and 10000.0000 easting. I backsight point number 101 with a backsight azimuth of 315d 00' 00". I store point number 101 as point number 1. I continue storing the remaining calculated points as side shots.
Surveyed Points:
Point Northing Easting Description
1 10290.1000 9709.9000 PCP N&D
2 10000.0000 10000.0000 TRAVERSE POINT
3 9881.7000 10149.3000 PCP N&D
4 9968.0300 10093.1800 1/2" IRC
5 10008.8800 10049.2500 1/2" IRC
6 10067.5100 10103.7000 1/2" IRC
7 10026.6100 10147.6000 1/2" IRC
Now I want to compare my surveyed points with my calculated points. My random point file (points to be transformed) is entered as 1.7 (range of points). In the transformation program I enter point number 101 as the old point (rotation point), and point number 1 as the new point. I enter 315d 00' 00" as my rotation angle.
Transformed Points:
Point Northing Easting Description
1 17785.4400 9723.8900 PCP N&D
2 17785.4400 10134.1600 TRAVERSE POINT
3 17807.3500 10323.3800 PCP N&D
4 17828.7100 10222.6500 1/2" IRC
5 17826.5400 10162.7000 1/2" IRC
6 17906.5000 10159.7500 1/2" IRC
7 17908.6200 10219.7100 1/2" IRC
As you can see, the resulting coordinates are incorrect. What did I do wrong?
Regards,
Mark
Do you have a manual for v7?
My email is posted, contact me about a manual.
Hello A Harris,
Thanks for the reply! I have a 1997 user's guide because I used to own a DCE card years ago. Last year I purchased the CVC Version 7 card on eBay. I worked through the example in the user's guide without any problems. I think my problem is the field methodology I'm using is faulty.
Regards,
Mark
I've never had a chance to use SMI software but from the looks of it you might have tried to wrap a coordinate transformation and coordinate rotation into the same process and the answer may have gotten lost in the process. I'm too lazy to take apart an hypothetical coordinate list with the calculator.
Start With Two Point Free Station (2PFS)
Set up across the street, Backsight A (known point 100) Foresight B (known point 101) store occupied point as number say 9. Occupy 9, BS 100, Sideshot 100, store as 10, BS 10, Sideshot 101, store as 11, continue field work.
Assume 101 and 11 do not agree, but 103 and 13 are a better fit, so let's adjust.
RPTS 9.15
CX
DeltaNEZ, old 10, new 100
Exit
Run
check that 10-100=0.000
Now rotate, yes you can do both together, but doing them separately is more sure footed.
RPTS 9.15
CX
ROT
ROTPT 100
ROTATE
OLD Angle 10 13
NEW Angle 100 103
EXIT
RUN
check again
If you are going for it all on one shot, be slow and sure about your entries.
I have tried it by entering a rotation angle, and then had to enter a minus rotation angle twice to get it right. Direction by point to point is easier to visualize.
Paul in PA
Hello R.J.,
Thanks for the reply! My boss uses a TDS COGO card, so he wants me to learn how to transform coordinates with my SMI card. He claims the TDS card has a glitch in its transformation program, but he knows a work-around for it. Are you kidding about doing a translation and rotation at the same time? We're surveying in the twenty first century here!
Regards,
Mark
Start With Two Point Free Station (2PFS)
Hello Paul,
Thanks for the reply! My boss's surveying philosophy is to transform field points to calculated points, then compare their positions. I've never surveyed like that before. I asked him "How can we use this traverse point, that has no value, to locate field points?" He told me to assign assumed coordinates to it, preferably much larger values than he uses for the calculated points. I also asked him what backsight bearing I should use. He told me it doesn't matter. Thanks for the keystroke examples! I will try them out later today.
Regards,
Mark
From v7 Manual
Probably what you would like -
Comparing surveyed (Measured), NM, EM, to Calculated, NC, EC
Results, from least squares "best fit" transformation solution, are as follows:
Calculated Measured ... Transformed .. Residuals
PtC NC EC PtM NM EM ... NT ET .. vN vE
100 5000 5000 3 9881.70 10149.30 ... 4999.978 4999.905 .. -0.022 -0.095
101 5000 4400 1 10290.10 9709.90 ... 4999.988 4400.019 .. -0.012 0.019
102 5025 4900 4 9968.03 10093.18 ... 5025.008 4900.025 .. 0.008 0.025
103 5025 4840 5 10008.88 10049.25 ... 5025.023 4840.037 .. 0.023 0.037
104 5105 4840 6 10067.51 10103.70 ... 5105.037 4840.007 .. 0.037 0.007
105 5105 4900 7 10026.61 10147.60 ... 5104.965 4900.007 .. -0.035 0.007
2 10000.00 10000.00 ... 4984.990 4810.008
Translation:
dN = -9147.692132
dE = 4293.002113
Rotation:
317°05'42.3"
Scale: Not applied to transformed coordinates
1.000 047 (for analysis only)
I believe SMI provides a solution based on the position of one point and the direction to a second point.
Ok... first off, you need to move your points 1 thru 7 (1.7) since they are at 10000s and your calc points are at 5000s. So you do the random pts (rpts) and put in 1.7. Then you choose cx to move the points. Using number 1 as the old and 101 as the new. It should give you a delta n and delta e. Then you can also rotate using 101 and the bearing. Does that make sense? Then you can inverse between points to see the differences. Kind of a rough way to see differences, but works in the field.
Whatever you do, be sure to re-do your setup. SMI WILL hold the old coords for your inst and bs unless you re-do your setup.
Don't ask me why I know that one!