TI media Finite Different Modeling and Reverse Time Migration

Rong Tao

• 👋 Hi, I’m @rtoax, you can see me in @linux-visor too.
• 👀 I’m interested in Linux
• 🌱 I’m currently learning Linux
• 💞️ I’m looking to collaborate on libcareplus, test-linux and more.
• 📫 How to reach me GitHub, CSDN, Gitee and Linux Newbie.

Aspect

• (2-dimension and 3-dimension)
• anisotropy media (VTI, TTI)
• Reverse Time Migration
• Finite Different Modeling
• Angle Domain Common Imaging Gathers (ADCIGs)
• Poynting vector methods

Author

Rong Tao RToax

wave equation

Migration

poynting vector

use Laplacian factor tobe a filter decrease the low frequence signal(noise)

void laplac2_lop(int adj, int nz, int nx, float *in, float *out)
/*< linear operator > Copyright(C) Madagascar */
{
    int iz,ix,j;

    for (ix=0; ix < nx; ix++) {
	for (iz=0; iz < nz; iz++) {
	    j = iz+ix*nz;

	    if (iz > 0) {
		if (adj) {
		    out[j-1] -= in[j];
		    out[j]   += in[j];
		} else {
		    out[j] += in[j] - in[j-1];
		}
	    }
	    if (iz < nz-1) {
		if (adj) {
		    out[j+1] -= in[j];
		    out[j]   += in[j];
		} else {
		    out[j] += in[j] - in[j+1];
		}
	    }

	    if (ix > 0) {
		if (adj) {
		    out[j-nz] -= in[j];
		    out[j]    += in[j];
		} else {
		    out[j] += in[j] - in[j-nz];
		}
	    }
	    if (ix < nx-1) {
		if (adj) {
		    out[j+nz] -= in[j];
		    out[j]    += in[j];
		} else {
		    out[j] += in[j] - in[j+nz];
		}
	    }
	}
    }
}

Poynting Vector ADCIGs

__global__ void Poynting_Adcigs(int nnz, 
                                int nx, 
                                int nz, 
                                int npml, 
                                int nangle, 
                                int dangle, 
                                float *adcigs, 
                                float *s_P, 
                                float *s_Q, 
                                float *s_u, 
                                float *s_w, 
                                float *g_P, 
                                float *g_Q, 
                                float *g_u, 
                                float *g_w)
/**
 *  poynting vector extraction ADCIGs
 *    "Copyright(C) Madagascar:user/pyang/Mrtmadcig.c"
 */
{
    int id = threadIdx.x+blockDim.x*blockIdx.x;
    int ix = id/nz;
    int iz = id%nz;

    int ia = 0;

    float Ssx = -s_P[iz+npml+nnz*(ix+npml)]*s_u[iz+npml+nnz*(ix+npml)];
    float Ssz = -s_Q[iz+npml+nnz*(ix+npml)]*s_w[iz+npml+nnz*(ix+npml)];
    float Sgx =  g_P[iz+npml+nnz*(ix+npml)]*g_u[iz+npml+nnz*(ix+npml)];
    float Sgz =  g_Q[iz+npml+nnz*(ix+npml)]*g_w[iz+npml+nnz*(ix+npml)];

    float b1 =  Ssx*Ssx + Ssz*Ssz;
    float b2 =  Sgx*Sgx + Sgz*Sgz;
    float  a = (Ssx*Sgx + Ssz*Sgz)/(sqrtf(b1*b2)*(1 - 0.1));

    if(id<nx*nz) {

        if(a>=-1&&a<=1) {

          a = 0.5*acosf(a)*180.0/pi;
         ia = (int)(a/(dangle*1.0));
         
            if(ia<nangle) {
                adcigs[iz+nz*ia+nz*nangle*(id/nz)] 
                    += s_P[iz+npml+nnz*(ix+npml)]*g_P[iz+npml+nnz*(ix+npml)]
                      *cosf(ia*pi/180.0)*cosf(ia*pi/180.0)*cosf(ia*pi/180.0);
            }
        }
    }
}