. // Bossa example #3 - calibration jobs. // We maintain the following for each user: // nneg # of negative calibration jobs shown // nneg_err # of errors // npos // npos_err // // from these we derive // neg_err_rate // pos_err_rate // // a job is considered done if either // - N instances are positive and match within +- 20 pixels, // and prod(pos_err_rate)get_opaque_data(); $path = $info->path; page_head("Find the Ellipse"); echo "

Click on the center of the ellipse. If you don't see one, click here:

id>

"; page_tail(); } function job_issued($job, $inst, $user) { $insts = $job->get_instances(); if (count($insts) > 1) { $job->set_priority(0); } } function job_finished($job, $inst, $user) { $response = null; if (get_str('submit', true)) { $response->have_ellipse = 0; } else { $response->have_ellipse = 1; $response->cx = get_int('pic_x'); $response->cy = get_int('pic_y'); } $inst->set_opaque_data($response); // if this is a calibration job, update user's opaque data // if ($job->calibration) { $b = $user->bossa; $info = $job->get_opaque_data(); $answer = $info->answer; $u = $b->get_opaque_data(); if (!$u) { $u->npos = 0; $u->npos_err = 0; $u->nneg = 0; $u->nneg_err = 0; } if (compatible($response, $answer)) { if ($answer->have_ellipse) { $u->npos++; } else { $u->nneg++; } } else { if ($answer->have_ellipse) { $u->npos++; $u->npos_err++; } else { $u->nneg++; $u->nneg_err++; } } $b->set_opaque_data($u); return; } // now see if job is done // $insts = $job->get_finished_instances(); $n = count($insts); $results = null; $users = null; foreach ($insts as $inst) { $results[] = $inst->get_opaque_data(); $u = $inst->get_user(); $users[] = $u->bossa->get_opaque_data(); } // see if there's a negative consensus // $prob = 1; for ($i=0; $i<$n; $i++) { $r = $results[$i]; if ($r1->have_ellipse) continue; $u = $users[$i]; $prob *= $u->neg_err_rate; } if ($prob < PROB_LIMIT) { $job->set_state(BOSSA_JOB_DONE); return; } // see if there's a positive consensus // for ($i=0; $i<$n; $i++) { $r1 = $results[$i]; $u = $users[$i]; $prob = $u->pos_error_rate; for ($j=0; $j<$n; $j++) { if ($j == $i) continue; $r2 = $results[$j]; if (compatible($r1, $r2)) { $u2 = $users[$j]; $prob *= $u2->pos_err_rate; } } if ($prob < PROB_LIMIT) { $job->set_state(BOSSA_JOB_DONE); return; } } // see if there are too many instances without a consensus // if ($n >= 10) { $job->set_state(BOSSA_JOB_INCONCLUSIVE); return; } // still looking for consensus - get another instance // $job->set_priority(2); } // two results are compatible if neither found an ellipse, // or they both did and centers are within 20 pixels // function compatible($r1, $r2) { if ($r1->have_ellipse) { if ($r2->have_ellipse) { $dx = ($r1->cx - $r2->cx); $dy = ($r1->cy - $r2->cy); $dsq = $dx*$dx + $dy*$dy; return ($dsq < 400); } else return false; } else { return !$r2->have_ellipse; } } function job_timed_out($job, $inst, $user) { $job->set_priority(1); } function job_summary($job) { $info = $job->get_opaque_data(); return "path>(view image)"; } function instance_summary($info) { if ($info->have_ellipse) { return "ellipse ($info->cx, $info->cy)"; } else { return "no ellipse"; } } function user_summary($user) { $b = $user->bossa; $info = $b->get_opaque_data(); if ($info) { if ($info->npos) { $pos_err = $info->npos_err/$info->npos; } else { $pos_err = "---"; } if ($info->nneg) { $neg_err = $info->nneg_err/$info->nneg; } else { $neg_err = "---"; } return "error rate: positive $pos_err ($info->npos_err/$info->npos), negative $neg_err ($info->nneg_err/$info->nneg) "; } else { return "No data"; } } ?>