Velodyne DIGITAL DRIVE - REV G Instrucciones de operaciones descargar pdf (Pagina 35)

APPENDIX F: DUAL TWO POINT CALIBRATION METHODOLOGY

and

’

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.

(

focalDistance

)

oca

Offset = 256

13100

distance

)

intensityVal

+ K | focalOffset - 256 (

65535

Here K is the slope from the calibration data. Intensity

gets

its

maximum

the

focal

distance

for

different

channels and from

its calibration data.

Calibration

indow

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_FlRlNG; i++) {

guit laser = i + base;

if (!db—>getEnabled(laser))

continue;

bool intensity =db—>getlntensity(laser); if

(!intensity: { glColor3fv(db—

>getDisplayColor(laser).rgb);

} else {

guchar minlntensity = 0, maxlntensity = 0;

float intensityScale = 0;

minlntensity = db—>getMinlntensity(laser);

maxlntensity = db—>getMaxlntensity(laser);

//Get intensity scale

intensityScale = (float)(maxlntensity — minlntensity);

// Get

guchar

firing “i” intensity

// Get

intensityVal = it—>getPoint(i)—

intensity;

firing “i” distance, here unit is 2mm

distance = it—>getPoint(i)—>distance;

float

// Calculate offset according calibration

float focaloffset= 256*(/—db—>getFocalDistance(laser)//3/00)*(/—db—

>getFocalDistance(laser)//3/00);

// get slope from calibration

float focalslope = db—>getFocalSlope(laser);

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Velodyne DIGITAL DRIVE - REV G Instrucciones de operaciones Pagina 35

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