# [Proj] Correction of definition of CRS EPSG 5456 and 5457

Eduardo Rojas Rodríguez eduardo.rojas at soltig.net
Sun Jan 21 21:51:03 EST 2018

```Hi Andre

sorry for bothering you again

I have read extensively all the information you have given me and I have
come to the following conclusions:

1. according to
and
http://geotiff.maptools.org/proj_list/lambert_conic_conformal_2sp.html

By having proj LCC 1SP with a scale factor is basically the same as LCC 2SP.
so the definition within PROJ4
+ proj = lcc + lat_1 = 10.46666666666667 + lat_0 = 10.46666666666667 + lon_0
= -84.33333333333333 + k_0 = 0.99995696 + x_0 = 500000 + y_0 = 271820.522 +
ellps = clrk66 + towgs84 = 205.96, -98.0.0.0.0 + units = m + no_defs

is correct since it determines lat_1 equal to lat_0

is this correct?

1. Regarding the "toWGS84" + towgs84 = 205.96, -98.0,0.0.0
is a concatenation (via NAD27) of the transformations 6888 and 1171 imported
from GDAL when using this transformation I get a displacement of 2mm

3. + towgs84 = 213.116,9.358, -74.946 are within the transformation EPSG ::
5470 Coordinate Transformation [Ocotepeque 1935 to WGS 84 (1)] which is more
general and I get displacements of 8 meters

As far as I can deduce, the definition is adequate both when using LCC1
which is equal to LCC2 with the scale factor.

the only thing then is to ask the EPSG for a transformation of EPSG :: 5470
Coordinate Transformation [Ocotepeque 1935 to WGS 84 (1) more presiding
using 7 parameters. maybe?

I would like to know what you think of my conclusions, so I can tell you how
much I have learned from PROJ4 and EPSG.

Thank you very much for all the help and everything I've learned

-----
Eduardo Rojas Rodríguez
Analista en SIG
Soluciones en Tecnologías
Tel: 506 2505-5453
eduardo.rojas at soltig.net
http://soltig.net

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Sent from: http://osgeo-org.1560.x6.nabble.com/PROJ-4-f3840930.html
```