Help creating a .prj file for Local Mine Grid

[SuperNewb]

Hi Guys,

I am having a hard time trying to wrap my head around building this .prj file and getting it to work inside PS Pro.

I have a set of images from my client that I assume they screen capped from MineSite.  I have put a word doc together with all the info contained in the images to make this easier.   I am hoping that someone can help me use this information to put together  a working .prj file that photoscan can read.


Much thanks,

Matt

Edit:

I am using Global Mapper to help me sort this out.  It appears however that the .prj files GM creates are not directly compatible with PS.  I have attached 2 UTM NAD83 10N .prj files, one from PS and one from GM.  It looks like the authority tags are the only difference.   What am I missing here, do I need to find Authority tags to let me create a .prj file for PS?

[Paulo]

Hi Matt,

from your text file and origin coordinates, it is clear that the projected coordinate system refers to UTM 10 in BC. Thus the official datum is NAD83(CSRS) and unit is meter but the doc specifies survey feet. So I took a NAD83 (CSRS) UTM10 prj and adapted it in feet....

However once you have these coordinates it seems that they have a local CS with parameters defined in Adjustments section

Attached is the prj with UNIT US Ft

[SuperNewb]

Thanks Pap1956,

I was able to get a version up and working yesterday.  However I am uncertain if NAD83 CSRS is the correct datum.

In the info supplied to me, it makes reference to the WGS84 ellipsoid model, so I added that in there rather than Nad83. 

Am I wrong for doing this?  It seems to be working.

Also, I haven't dug into it too hard but do you think I will be able to use the TOWGS84 to apply the coordinate shifts and rotations necessary?

Here is what I am working with right now.

[Paulo]

Matt,

if the WGS84 datum is specified then you can go ahead with that. The only thing is that in your prj, the false easting is wrong

PARAMETER["false_easting",500000]

it should be PARAMETER["false_easting",1640416.667]. as unit is feet and not meter.

As for the rotation and shift part of your local coordinate system, the TOWGS84 entry does not cover that as this is a 7 parameter similarity transformation between 2 3d datums.

You would have to do that outside of Photoscan, for example in a cAD or Global Mapper.....

That is do everything in WGS84 UTM10, then export your products and apply 2 d shift, rotation and scale outside of PS.

[harrytwomey]

Hello, i have the same issue. just to clarify, are we saying it is impossible to create a .prj for local grids with rotations?

[harrytwomey]

Hello again, i doing a bit more searching on this and im wondering if it would be possible to use a different projection system to achive the desired results.

I have the data used by Trimble Business Center to do surveys on the mine site local grid
It seem that, as mention above, the rotation is not a function of the transverse Mercator projection, but there are other mercator projections that might be able to do the rotations

On the Survey Logger the data in in 4 section for the local min grid (angles are in DMS)

Section 1-  Projection
Type: Transverse Mercator
False Northing: 11972.950
False Easting: 8987.834
Origin Lat: 53 40 52.58768N
Origin Long: 6 42 39.72438W
Scale Factor 1.000166700
Semi-Major Axis: 6378137.000
Flattening: 298.2572229329
Use Shift Grid: NO
Coordinates: Grid
Project Height: 1600

Section 2- Datum Transformation
Type: Three Parameter
Semi-Major Axis: 6378137.0
Flattening: 298.2572229329
Translation X: 0.0
Translation Y: 0.0
Translation Z: 0.0

Section 3- Horizontal Adjustment
Type: Plane
Origin North: 12312.624
Origin East: 8993.824
Translation North: -4.141
Translation East: -59.232
Rotation: -10 01 31.260633
Scale Factor: 1.00000199

Section 1- Vertical Adjustment
Type: Inclined Plane
Origin North: 11972.952
Origin East: 8987.826
Slope North: 0.000ppm
Slope East: 0.000ppm
Constant Adjustment : 1477.519


I found this http://docs.opengeospatial.org/is/12-063r5/12-063r5.html what explains the different parameters of the projections and there uses, at the bottom of the page

But from my looking maybe we can use a Hotine Oblique Mercator (variant A) or (variant B) to achieve the desired results.

If anyone out there has some understanding of these, maybe their is some help you can give