Velodyne Acoustics HDL-64E S2 user manual Intensity Compensation vs Distance, Calibration Window

aPPendix f: duaL tWo Point caLiBration MethodoLoGy

HDL-64E S2 and S2.1 User’s Manual

Intensity Compensation vs Distance

Intensity compensation is done in the software for different channels by changing a parameter in the calibration window until the measurement gets to a uniform intensity for a reference target.

focalOffset = 256 (	1 - focalDistance		2
	______________ )
	13100
	1 - distance			2	]
intensityVal = intensityVal + K [ focalOffset - 256 ( __________ )
		65535

Here K is the slope from the calibration data. Intensity gets to its maximum at the focal distance for different channels and from its calibration data.

Calibration Window

The following new intensity parameters have been added in the db.xml calibration file

•focal distance: At this distance, the intensity goes to max. The focal distance is different from laser to laser. On the upper block, it averages 1500cm. On the lower block, it averages 800cm.

•focal slope: This parameter controls intensity compensation. Min and Max Intensity are used to scale and offset intensity.

Intensity Value Corrected by Distance Code

for (guint i=0; i< VLS_LASER_PER_FIRING; i++) { guit laser = i + base;

if (!db->getEnabled(laser)) continue;

bool intensity =db->getIntensity(laser); if (!intensity: { glColor3fv(db->getDisplayColor(laser).rgb); } else {

guchar minIntensity = 0, maxIntensity = 0; float intensityScale = 0;

minIntensity = db->getMinIntensity(laser); maxIntensity = db->getMaxIntensity(laser); //Get intensity scale

intensityScale = (float)(maxIntensity - minIntensity); // Get firing “i” intensity

guchar intensityVal = it->getPoint(i)->intensity;

//Get firing “i” distance, here unit is 2mm float distance = it->getPoint(i)->distance;

//Calculate offset according calibration

float focaloffset= 256*(1-db->getFocalDistance(laser)/13100)*(1-db- >getFocalDistance(laser)/13100);

// get slope from calibration

float focalslope = db->getFocalSlope(laser);

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