INTRODUCTION

The TransLT library offers the following functionalities:

The transformation of coordinates between two coordinates systems;
Drawing polygons, paths or points in Google Earth.

Supported coordinate operations:

coordinates conversions (including the use of a map projection);
transformations with parameters: 1D, 2D or 3D;
polynomial transformations;
coordinates offset using grid files;
coordinates offset;
transformations with own formulas.

Coordinate transformation can be done based on a transformation model that is taken from a file, a model that contains operations with coordinates defined as transformation steps. If the transformation model supports the inverse calculation then the transformation can be done in reverse.

To create files with transformation models, we recommend that you use the main TransLT application where you can create and test transformation models. Also in the main application you can use the EPSG database to automatically create transformation steps. For this it is necessary to have a minimum of knowledge about coordinate reference systems (CRS) and about possible coordinate operations (CooOp) between these systems. Another important factor is the accuracy of the transformation that you need to know before making a new transformation model. It would be useful to have one or more points with coordinates in both systems to test the newly created model. If you can't handle it, please write to us at support@3dspace.ro, and if possible we will create the transformation model for you.

In the "Examples" folder you will find information about the implementation in Delphi and in Visual Studio, including the compiled executables. Also here you will find examples with some of the supported file types (transformation models, files with coordinates, files with graphic entities, etc.).

In the "Demo_TransLT_Library.exe" test application window you have exemplified how to make the settings in the "Language settings" and "Model properties" section and four usage examples in the sections: "Transformation test file", "Test for one point", "Test for entities file" and "Define entities, transform points and draw to Google Earth".

Note on the choice of operating system 32bit or 64bit: For 32-bit operating systems TransLT.Win32.dll library operate with 80 bits (10 bytes) allocated to real numbers, about 19 to 20 significant digits and for 64-bit operating systems TransLT.Win64.dll library operate with 64 bits (8 bytes) allocated to real numbers, about 15 to 16 significant digits.

Supported Conversions and Transformations

Coordinates conversions

Type of source coordinates		Type of target coordinates
Geographical coordinates (φ,λ,h)	→	Geocentric cartesian coordinates (X,Y,Z)
Geocentric cartesian coordinates (X,Y,Z)	→	Geographical coordinates (φ,λ,h)
Geographical coordinates (φ,λ)	→	Plane coordinates (N,E) according to selected projection
Plane coordinates (N,E)	→	Geographical coordinates (φ,λ) according to selected projection

Projections

Cylindrical Projections
No.	Projection name	Applicable on ellipsoid	Applicable on spheroid	Reversible
1	Cassini-Soldner	√	√	√
2	Central Cylindrical		√	√
3	Cylindrical Equal Area (Normal)	√	√	√
4	Cylindrical Equal Area (Oblique)	√	√	√
5	Cylindrical Equal Area (Transverse)	√	√	√
6	Equidistant Cylindrical	√	√	√
7	Gall Stereographic Cylindrical		√	√
8	Hotine Oblique Mercator (Variant A)	√	√	√
9	Hotine Oblique Mercator (Variant B)	√	√	√
10	Hyperbolic Cassini-Soldner	√		√
11	Laborde for Madagascar	√	√	√
12	Mercator (1SP) (Variant A)	√	√	√
13	Mercator (2SP) (Variant B)	√	√	√
14	Mercator (2SP) (Variant C)	√	√	√
15	Miller Cylindrical		√	√
16	Popular Visualisation Pseudo Mercator	√	√	√
17	Swiss. Obl. Mercator	√	√	√
18	Transverse Mercator	√	√	√
19	Transverse Mercator (South Orientated)	√	√	√
20	Transverse Mercator Zoned Grid System	√	√	√
21	Tunisia Mining Grid	√	√	√
22	Universal Transverse Mercator (UTM)	√	√	√
Pseudocylindrical Projections
23	Collignon		√	√
24	Eckert I		√	√
25	Eckert II		√	√
26	Eckert III		√	√
27	Eckert IV		√	√
28	Eckert V		√	√
29	Eckert VI		√	√
30	Equal Earth	√	√	√
31	Fahey (Modified Gall)		√	√
32	Foucaut Sinusoidal		√	√
33	Foucaut Stereographic Equivalent		√	√
34	Hatano Asymmetrical Equal Area		√	√
35	Kavraiskiy V		√	√
36	Kavraiskiy VII		√	√
37	Loximuthal		√	√
38	McBride-Thomas Flat-Polar Parabolic (No. 5)		√	√
39	McBryde-Thomas Flat-Polar Quartic (No. 4)		√	√
40	McBryde-Thomas Flat-Polar Sine (No. 1)		√	√
41	McBryde-Thomas Flat-Polar Sinusoidal (No. 3)		√	√
42	McBryde-Thomas Flat-Pole Sine (No. 2)		√	√
43	Mollweide		√	√
44	Nell		√	√
45	Nell-Hammer		√	√
46	Pseudo Plate Carrée	√	√	√
47	Putnins P1		√	√
48	Putnins P2		√	√
49	Putnins P3		√	√
50	Putnins P3p		√	√
51	Putnins P4 (Craster Parabolic)		√	√
52	Putnins P4p		√	√
53	Putnins P5		√	√
54	Putnins P5p		√	√
55	Putnins P6		√	√
56	Putnins P6p		√	√
57	Quartic Authalic		√	√
58	Sinusoidal (Sanson-Flamsteed)	√	√	√
59	Wagner I (Kavraiskiy VI)		√	√
60	Wagner II		√	√
61	Wagner III		√	√
62	Wagner IV		√	√
63	Wagner V		√	√
64	Wagner VI		√	√
65	Werenskiold I		√	√
66	Winkel I		√	√
67	Winkel II		√
Conic Projections
68	Albers Equal Area	√	√	√
69	Bipolar conic of western hemisphere		√	√
70	Equidistant Conic	√	√	√
71	Euler (Equidistant Conic)		√	√
72	Krovak Oblique Conformal Conic	√	√	√
73	Krovak Oblique Conformal Conic (North Orientated)	√	√	√
74	Krovak Oblique Conformal Conic Modified	√	√	√
75	Krovak Oblique Conformal Conic Modified (North Orientated)	√	√	√
76	Lambert Conformal Conic (1SP)	√	√	√
77	Lambert Conformal Conic (1SP variant B)	√	√	√
78	Lambert Conformal Conic (1SP) West Orientated	√	√	√
79	Lambert Conformal Conic (2SP)	√	√	√
80	Lambert Conformal Conic (2SP) Belgium	√	√	√
81	Lambert Conformal Conic (2SP) Michigan	√	√	√
82	Lambert Conic Near-Conformal	√		√
83	Murdoch I (Equidistant Conic)		√	√
84	Murdoch II		√	√
85	Murdoch III (Equidistant Conic, minimum error)		√	√
86	Perspective Conic		√	√
87	Tissot		√	√
88	Vitkovskiy I (Equidistant Conic)		√	√
Pseudoconic Projections
89	Bonne (South Orientated)	√	√	√
90	Bonne (Werner for lat.1sp = 90°)	√	√	√
Polyconic Projections
91	American Polyconic	√	√	√
92	International Map of the World (Modified Polyconic)	√	√	√
Azimuthal Projections
93	Azimuthal Equidistant	√	√	√
94	Colombia Urban Projection	√	√	√
95	Gnomonic		√	√
96	Guam (Azimuthal Equidistant)	√		√
97	Lambert Azimuthal Equal Area	√	√	√
98	Lee Oblated Stereographic		√	√
99	Miller Oblated Stereographic		√	√
100	Mod. Stererographics of 48 U.S.		√	√
101	Mod. Stererographics of 50 U.S.	√	√	√
102	Mod. Stererographics of Alaska	√	√	√
103	Modified Azimuthal Equidistant (for Micronesia)	√		√
104	Oblique Stereographic	√	√	√
105	Orthographic	√	√	√
106	Polar Stereographic Variant A (Universal)	√	√	√
107	Polar Stereographic Variant B	√	√	√
108	Polar Stereographic Variant C	√	√	√
109	Stereographic (J.P. Snyder formulas)	√	√	√
110	Topocentric local	√	√	√
111	Vertical Perspective	√	√
112	Vertical Perspective (Orthographic case)	√	√
Miscellaneous Projections
113	New Zealand Map Grid	√		√
114	Van der Grinten		√	√

Transformations with parameters

Transformation type	Method	No. parameters	Invertible parameters	Reversible
Transformation 1D	3D plane rotation	5		√
Transformation 1D	Translate to elevation	1	√	√
Transformation 2D	2D Helmert conformal transformation	4	√	√
	2D Helmert conformal transformation with rotation origin	6		√
	2D orthogonal affine transformation	5		√
	2D non-orthogonal affine transformation	6	√	√
Transformation 3D	3D Helmert, Bursa-Wolf method, conformal transformation	7	√	√
	3D Helmert, Molodenski-Bedekas, conformal transformation	10
	3D Helmert conformal transformation	7	√	√
	3D affine transformation	8
	3D affine transformation	9
	3D affine transformation with rotation origin	12
	Time-dependent 3D transformation, Bursa-Wolf method	15	√	√
	Time-dependent 3D transformation, Helmert conformal	15		√

Polynomials transformations

Method name	Polynomials degree	Reversible
General polynomial	2
	3
	4
	6
	13
Reversible polynomial	2	√
	3	√
	4	√
	6	√
	13	√
Complex polynomial	3
Complex polynomial	4
Madrid to ED50 polynomial	1

Grid files

File extension	Format	File description	Applied to
.94	Binary	Geoid model VERTCON format	h
.asc	ASCII	Geoid model ASC format	h
.b	Binary	NADCON 5, GEOCON, GEOCON 11 or VERTCON 3.0 format	(φ,λ,h), (φ,λ) or h
.bin	Binary	Geoid model NGS format	h
.byn	Binary	Geoid model GSD format	h
.csv	ASCII	Geoid model NZLVD (New Zealand) or BEV AT (Austria) format	h
.dat	Binary	NTv1 format	(φ, λ)
.dat	ASCII	Geoid model DAT format	h
.ggf	Binary	Geoid model Trimble GGF format	h
.grd	Binary	ANCPI 1D or 2D format (Romania)	(N, E) or h
.grd	ASCII	EGM96 geoid model, NGA format	h
.gri	ASCII	Geoid model Gravsoft (OSGM15) format	h
.gsb	Binary	NTv2 format, files with multiple grids that cover more areas, the gridscan have sub-grids attached	(φ, λ) or h
.gsf	ASCII	Geoid model Carlson SurvCE GSF format	h
.gtx	Binary	Geoid model GTX format	h
.gvb	Binary	Point motion NTv2_Vel format, files with multiple grids that cover more areas, the gridscan have sub-grids attached	(φ, λ, h)
.gz	Archive	EGM2008 geoid model, NGA format	h
.las / .los	Binary	NADCON format	(φ, λ)
.lla	ASCII	Latitude and longitude corrections in PROJ4 format	(φ, λ)
.mnt	ASCII	IGN with MNT format	(φ, λ) or h
.sid	ASCII	Geoid model NZGV format	h
.txt	ASCII	IGN with TXT format	(φ, λ) or h
.txt	ASCII	OSTN02/OSGM02 or OSTN15/OSGM15 1D or 3D format	(N,E,H), (N,E) or H
.txt	ASCII	Geoid model CING11 format	h
gugik*.txt	ASCII	GUGiK PL TXT format	(φ, λ, h) or h
.isg.txt	ASCII	Geoid model ISG format	h
.zip	Archive	Deformation model NZGD2000 format	(φ,λ,h), (φ,λ) or h
Grid interpolation methods: Bilinear, Bicubic spline and Biquadratic.

Offset methods

Method name	Applied to	Reversible
Longitude rotation	λ	√
Vertical Offset	h	√
Vertical Offset and Slope	h	√
Geographic 2D offsets	(φ, λ)	√
Geographic 2D with Height Offsets	(φ, λ, h)	√
Geographic 3D offsets	(φ, λ, h)	√
Geographic 3D to 2D conversion	h = 0.0	√
Geographic 2D axis order reversal	(φ, λ)	√
Geographic 3D axis order change	(φ, λ)	√
Change of vertical axis direction	h	√
Change of horizontal axes directions	(φ, λ), (N, E)	√
Change of all axes directions	(N, E, H), (X, Y, Z)	√
Change of vertical axis unit	h	√
Change of horizontal axes units	(φ, λ), (N, E)	√
Change of all axes units	(N, E, H), (X, Y, Z)	√
Points motion (ellipsoidal)	(φ, λ, h)	√
Change zero-tide height to mean-tide height	h	√

Predefined constants and functions for transformations with own formulas

Name	Description	Example
pi	Pythagorean number pi = 3.141592655...
e	Euler number e = 2.71828182...
abs	absolute value	abs(-1.0) = 1.0 abs(1.0) = 1.0
sqrt	square root	sqrt(2.0) = 1.41421356...
pow(B,n)	raises base B to power n	pow(25,1.5) = 125.0
ln	natural logarithm	ln(e) = 1.0
sin	sine calculated for angles in radians	sin(pi/2) = 1.0
cos	cosine calculated for angles in radians	cos(pi/2) = 0.0
tan	tangent calculated for angles in radians	tan(pi/4) = 1.0
asin	arcsine, the return value will fall in the range [-pi/2, pi/2]	asin(1.0) = pi/2
acos	arccosine, the return value will fall in the range [0, pi/2]	acos(0.0) = pi/2
atan	arctangent, the return value will fall in the range [-pi/2, pi/2]	atan(1.0) = pi/4
atan2(dy,dx)	arctangent angle and quadrant, the return value will fall in the range [-pi, pi](all quadrants)	atan2(-5.0,0.0) = -pi/2
sinh	hyperbolic sine	sinh(ln(2.0)) = 0.75
cosh	hyperbolic cosine	cosh(ln(2.0)) = 1.25
tanh	hyperbolic tangent	tanh(ln(2.0)) = 0.6
asinh	hyperbolic arcsine	asinh(0.75) = ln(2.0)
acosh	hyperbolic arccosine	acosh(1.25) = ln(2.0)
atanh	hyperbolic arctangent	atanh(0.6) = ln(2.0)
rtod	conversion from radians to decimal degrees	rtod(pi) = 180.0
dtor	conversion from decimal degrees to radians	dtor(180.0) = pi