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/******************************************************************************
* Project: SCH Coordinate system
* Purpose: Implementation of SCH Coordinate system
* References :
* 1. Hensley. Scott. SCH Coordinates and various transformations. June 15, 2000.
* 2. Buckley, Sean Monroe. Radar interferometry measurement of land subsidence. 2000..
* PhD Thesis. UT Austin. (Appendix)
* 3. Hensley, Scott, Elaine Chapin, and T. Michel. "Improved processing of AIRSAR
* data based on the GeoSAR processor." Airsar earth science and applications
* workshop, March. 2002. (http://airsar.jpl.nasa.gov/documents/workshop2002/papers/T3.pdf)
*
* Author: Piyush Agram (piyush.agram@jpl.nasa.gov)
* Copyright (c) 2015 California Institute of Technology.
* Government sponsorship acknowledged.
*
* NOTE: The SCH coordinate system is a sensor aligned coordinate system
* developed at JPL for radar mapping missions. Details pertaining to the
* coordinate system have been release in the public domain (see references above).
* This code is an independent implementation of the SCH coordinate system
* that conforms to the PROJ.4 conventions and uses the details presented in these
* publicly released documents. All credit for the development of the coordinate
* system and its use should be directed towards the original developers at JPL.
******************************************************************************
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS
* OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
* THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
* FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
* DEALINGS IN THE SOFTWARE.
****************************************************************************/
#define PJ_LIB__
#include <errno.h>
#include <math.h>
#include "proj.h"
#include "proj_internal.h"
namespace { // anonymous namespace
struct pj_opaque {
double plat; /*Peg Latitude */
double plon; /*Peg Longitude*/
double phdg; /*Peg heading */
double h0; /*Average altitude */
double transMat[9];
double xyzoff[3];
double rcurv;
PJ* cart;
PJ* cart_sph;
};
} // anonymous namespace
PROJ_HEAD(sch, "Spherical Cross-track Height") "\n\tMisc\n\tplat_0= plon_0= phdg_0= [h_0=]";
static PJ_LPZ sch_inverse3d(PJ_XYZ xyz, PJ *P) {
struct pj_opaque *Q = static_cast<struct pj_opaque*>(P->opaque);
PJ_LPZ lpz;
lpz.lam = xyz.x * (P->a / Q->rcurv);
lpz.phi = xyz.y * (P->a / Q->rcurv);
lpz.z = xyz.z;
xyz = Q->cart_sph->fwd3d (lpz, Q->cart_sph);
/* Apply rotation */
xyz = {
Q->transMat[0] * xyz.x + Q->transMat[1] * xyz.y + Q->transMat[2] * xyz.z,
Q->transMat[3] * xyz.x + Q->transMat[4] * xyz.y + Q->transMat[5] * xyz.z,
Q->transMat[6] * xyz.x + Q->transMat[7] * xyz.y + Q->transMat[8] * xyz.z
};
/* Apply offset */
xyz.x += Q->xyzoff[0];
xyz.y += Q->xyzoff[1];
xyz.z += Q->xyzoff[2];
/* Convert geocentric coordinates to lat lon */
return Q->cart->inv3d (xyz, Q->cart);
}
static PJ_XYZ sch_forward3d(PJ_LPZ lpz, PJ *P) {
struct pj_opaque *Q = static_cast<struct pj_opaque*>(P->opaque);
/* Convert lat lon to geocentric coordinates */
PJ_XYZ xyz = Q->cart->fwd3d (lpz, Q->cart);
/* Adjust for offset */
xyz.x -= Q->xyzoff[0];
xyz.y -= Q->xyzoff[1];
xyz.z -= Q->xyzoff[2];
/* Apply rotation */
xyz = {
Q->transMat[0] * xyz.x + Q->transMat[3] * xyz.y + Q->transMat[6] * xyz.z,
Q->transMat[1] * xyz.x + Q->transMat[4] * xyz.y + Q->transMat[7] * xyz.z,
Q->transMat[2] * xyz.x + Q->transMat[5] * xyz.y + Q->transMat[8] * xyz.z
};
/* Convert to local lat,lon */
lpz = Q->cart_sph->inv3d (xyz, Q->cart_sph);
/* Scale by radius */
xyz.x = lpz.lam * (Q->rcurv / P->a);
xyz.y = lpz.phi * (Q->rcurv / P->a);
xyz.z = lpz.z;
return xyz;
}
static PJ *destructor (PJ *P, int errlev) {
if (nullptr==P)
return nullptr;
auto Q = static_cast<struct pj_opaque*>(P->opaque);
if( Q )
{
if (Q->cart)
Q->cart->destructor (Q->cart, errlev);
if (Q->cart_sph)
Q->cart_sph->destructor (Q->cart_sph, errlev);
}
return pj_default_destructor(P, errlev);
}
static PJ *setup(PJ *P) { /* general initialization */
struct pj_opaque *Q = static_cast<struct pj_opaque*>(P->opaque);
/* Setup original geocentric system */
// Pass a dummy ellipsoid definition that will be overridden just afterwards
Q->cart = proj_create(P->ctx, "+proj=cart +a=1");
if (Q->cart == nullptr)
return destructor(P, PROJ_ERR_OTHER /*ENOMEM*/);
/* inherit ellipsoid definition from P to Q->cart */
pj_inherit_ellipsoid_def (P, Q->cart);
const double clt = cos(Q->plat);
const double slt = sin(Q->plat);
const double clo = cos(Q->plon);
const double slo = sin(Q->plon);
/* Estimate the radius of curvature for given peg */
const double temp = sqrt(1.0 - (P->es) * slt * slt);
const double reast = (P->a)/temp;
const double rnorth = (P->a) * (1.0 - (P->es))/pow(temp,3);
const double chdg = cos(Q->phdg);
const double shdg = sin(Q->phdg);
Q->rcurv = Q->h0 + (reast*rnorth)/(reast * chdg * chdg + rnorth * shdg * shdg);
/* Set up local sphere at the given peg point */
Q->cart_sph = proj_create(P->ctx, "+proj=cart +a=1");
if (Q->cart_sph == nullptr)
return destructor(P, PROJ_ERR_OTHER /*ENOMEM*/);
pj_calc_ellipsoid_params(Q->cart_sph, Q->rcurv, 0);
/* Set up the transformation matrices */
Q->transMat[0] = clt * clo;
Q->transMat[1] = -shdg*slo - slt*clo * chdg;
Q->transMat[2] = slo*chdg - slt*clo*shdg;
Q->transMat[3] = clt*slo;
Q->transMat[4] = clo*shdg - slt*slo*chdg;
Q->transMat[5] = -clo*chdg - slt*slo*shdg;
Q->transMat[6] = slt;
Q->transMat[7] = clt*chdg;
Q->transMat[8] = clt*shdg;
PJ_LPZ lpz;
lpz.lam = Q->plon;
lpz.phi = Q->plat;
lpz.z = Q->h0;
PJ_XYZ xyz = Q->cart->fwd3d (lpz, Q->cart);
Q->xyzoff[0] = xyz.x - (Q->rcurv) * clt * clo;
Q->xyzoff[1] = xyz.y- (Q->rcurv) * clt * slo;
Q->xyzoff[2] = xyz.z - (Q->rcurv) * slt;
P->fwd3d = sch_forward3d;
P->inv3d = sch_inverse3d;
return P;
}
PJ *PROJECTION(sch) {
struct pj_opaque *Q = static_cast<struct pj_opaque*>(calloc (1, sizeof (struct pj_opaque)));
if (nullptr==Q)
return pj_default_destructor(P, PROJ_ERR_OTHER /*ENOMEM*/);
P->opaque = Q;
P->destructor = destructor;
Q->h0 = 0.0;
/* Check if peg latitude was defined */
if (pj_param(P->ctx, P->params, "tplat_0").i)
Q->plat = pj_param(P->ctx, P->params, "rplat_0").f;
else {
proj_log_error(P, _("Missing parameter plat_0."));
return pj_default_destructor(P, PROJ_ERR_INVALID_OP_MISSING_ARG);
}
/* Check if peg longitude was defined */
if (pj_param(P->ctx, P->params, "tplon_0").i)
Q->plon = pj_param(P->ctx, P->params, "rplon_0").f;
else {
proj_log_error(P, _("Missing parameter plon_0."));
return pj_default_destructor(P, PROJ_ERR_INVALID_OP_MISSING_ARG);
}
/* Check if peg heading is defined */
if (pj_param(P->ctx, P->params, "tphdg_0").i)
Q->phdg = pj_param(P->ctx, P->params, "rphdg_0").f;
else {
proj_log_error(P, _("Missing parameter phdg_0."));
return pj_default_destructor(P, PROJ_ERR_INVALID_OP_MISSING_ARG);
}
/* Check if average height was defined - If so read it in */
if (pj_param(P->ctx, P->params, "th_0").i)
Q->h0 = pj_param(P->ctx, P->params, "dh_0").f;
return setup(P);
}
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