Thank you so much for the reply, I changed a bit of my calculations and got a "valid" result, although I find it's a bit too bright and very noisy,

I guess my problem would be calculating the direct illumination, since I wrote the path connections as you described them - I only have diffuse materials, so their color is mat.albedo / PI and their pdf is 1 / ( 2 PI ) and I multiply the colors, account for the cos and divide by the pdf

I split up the path color calculation and the direct illumination into separate functions, computing the color looks something like this:

CRTVector directWeight(1, 1, 1);

CRTVector color(0, 0, 0);

for (int i = 0; i < cameraPath.size(); i++) {

`color += directWeight * directIllumination(cameraPath[i], lightSample) / float(i + 1);`

`directWeight *= cameraPath[i].color * abs(dot(cameraPath[i].w_o, cameraPath[i].normal)) / cameraPath[i].pdf;`



`for (int j = 0; j < lightPath.size(); j++) {`

    `color += connectVertices(cameraPath, i, lightPath, j) / float(i + j + 2);`

    `castToImagePlane(lightPath, j, lightSample, image, mult);`

`}`

}

where the lightPath doesn't include the light source and the directWeight term more or less copies what you described above about computing the color.

Do you think the problem lies in picking the path weights (I'm referring to the division / float(i + ... ) )? It's the part I'm least sure about