inconsistent handling of the alpha value in PointCloudDepthAndRGBtoXYZRGBA

[csukuangfj]

Your Environment

• PCL Version: the master branch

Context

See the code

pcl/common/include/pcl/point_types_conversion.h

Lines 373 to 374 in 9467b94

	PointXYZRGBA pt;
	pt.a = 0;

alpha is set to 0.
But

pcl/common/include/pcl/impl/point_types.hpp

Lines 346 to 350 in 9467b94

	inline RGB ()
	{
	r = g = b = 0;
	a = 255;
	}

pcl/common/include/pcl/impl/point_types.hpp

Lines 352 to 358 in 9467b94

	inline RGB (uint8_t _r, uint8_t _g, uint8_t _b)
	{
	r = _r;
	g = _g;
	b = _b;
	a = 255;
	}

pcl/common/include/pcl/impl/point_types.hpp

Lines 560 to 566 in 9467b94

	inline PointXYZRGBA ()
	{
	x = y = z = 0.0f;
	data[3] = 1.0f;
	r = g = b = 0;
	a = 255;
	}

pcl/common/include/pcl/impl/point_types.hpp

Lines 627 to 633 in 9467b94

	inline PointXYZRGB ()
	{
	x = y = z = 0.0f;
	data[3] = 1.0f;
	r = g = b = 0;
	a = 255;
	}

pcl/common/include/pcl/impl/point_types.hpp

Lines 634 to 642 in 9467b94

	inline PointXYZRGB (uint8_t _r, uint8_t _g, uint8_t _b)
	{
	x = y = z = 0.0f;
	data[3] = 1.0f;
	r = _r;
	g = _g;
	b = _b;
	a = 255;
	}

pcl/common/include/pcl/impl/point_types.hpp

Lines 659 to 666 in 9467b94

	inline PointXYZRGBL ()
	{
	x = y = z = 0.0f;
	data[3] = 1.0f;
	r = g = b = 0;
	a = 255;
	label = 255;
	}

pcl/common/include/pcl/impl/point_types.hpp

Lines 667 to 676 in 9467b94

	inline PointXYZRGBL (uint8_t _r, uint8_t _g, uint8_t _b, uint32_t _label)
	{
	x = y = z = 0.0f;
	data[3] = 1.0f;
	r = _r;
	g = _g;
	b = _b;
	a = 255;
	label = _label;
	}

all set alpha to 255.

Expected Behavior

For consistency, alpha in PointCloudDepthAndRGBtoXYZRGBA should be set to 255 instead of 0.

Current Behavior

alpha in PointCloudDepthAndRGBtoXYZRGBA is set to 0.

Code to Reproduce

See the code above.

Possible Solution

Set alpha in PointCloudDepthAndRGBtoXYZRGBA to 255.

[taketwo]

Agree, alpha should be 255. Since it is already initialized inside the constructor, line 374 may be removed altogether.