what is the correct way of changing depth_scale?

[ywjia]

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Required Info
Camera Model	D435
Firmware Version	5.10.3.0
Operating System & Version	Ubuntu 16
Kernel Version (Linux Only)	4.15.0-34
Platform	PC
SDK Version	2.16.0
Language	C++
Segment	VR}

Issue Description

What is the correct way of setting depth_scale? I have the following code running, but the output puzzles me. See below. I would expect depth_scale_2 be the updated value 0.0001, not the original one (0.001).

int main()
{
rs2::context ctx;
auto list = ctx.query_devices();
if (list.size() == 0) throw std::runtime_error("No device detected. Is it plugged in?");
rs2::pipeline pipe;
rs2::config cfg;
cfg.enable_stream(RS2_STREAM_COLOR, 1920, 1080, RS2_FORMAT_BGR8, 15);
cfg.enable_stream(RS2_STREAM_DEPTH, 1280, 720, RS2_FORMAT_Z16, 15);
rs2::pipeline_profile profile = pipe.start(cfg);
rs2::depth_sensor depth_sensor = profile.get_device().firstrs2::depth_sensor();
auto original_scale = depth_sensor.get_option(RS2_OPTION_DEPTH_UNITS);
std::cout << "original scale: " << original_scale << std::endl;
float depth_scale_1 = get_depth_scale(profile.get_device());
std::cout << "depth_scale_1 = " << depth_scale_1 << std::endl;
depth_sensor.set_option(RS2_OPTION_DEPTH_UNITS, 0.0001);
auto updated_scale = depth_sensor.get_option(RS2_OPTION_DEPTH_UNITS);
std::cout << "updated scale: " << updated_scale << std::endl;
float depth_scale_2 = get_depth_scale(profile.get_device());
std::cout << "depth_scale_2 = " << depth_scale << std::endl;
return EXIT_SUCCESS;
}

output:

original scale: 0.001
depth_scale_1 = 0.001
updated scale: 0.0001
depth_scale_2 = 0.001

[RealSense-Customer-Engineering]

[Realsense Customer Engineering Team Comment]
Hi @ywjia,

Check below code. It should be no problem to modify the depth scale.

auto sensor = profile.get_device().firstrs2::depth_sensor();
auto depth_unit = sensor.get_option(RS2_OPTION_DEPTH_UNITS);
auto scale = sensor.get_depth_scale();
printf("[Before]Depth Scale: %f\r\n", scale);
sensor.set_option(RS2_OPTION_DEPTH_UNITS, 0.0001);
depth_unit = sensor.get_option(RS2_OPTION_DEPTH_UNITS);
scale = sensor.get_depth_scale();
printf("[After]Depth Scale: %f\r\n", scale);

[ywjia]

Hi @RealSense-Customer-Engineering,

I copy&paste and run your code above, but depth_scale was not changed, as output below:

[Before]Depth Scale: 0.001000
[After]Depth Scale: 0.001000

Of course, the first line was changed to
auto sensor = profile.get_device().first < rs2::depth_sensor >();

Also, what is the difference between "sensor.get_option(RS2_OPTION_DEPTH_UNITS)" and " get_depth_scale(profile.get_device())"?

Thanks.

[RealSense-Customer-Engineering]

[Realsense Customer Engineering Team Comment]
Hi @ywjia,

"RS2_OPTION_DEPTH_UNITS" and "get_depth_scale" can be used to get the value. But, you can use "RS2_OPTION_DEPTH_UNITS" before stream starts.
So, suggest to set the depth unit first, and then you should be able to get the correct scale value after pipe start. The example code like below:

rs2::context ctx; // Create librealsense context for managing devices
auto list = ctx.query_devices(); // Get a snapshot of currently connected devices
rs2::device dev = list.front();
auto depthSensor = dev.firstrs2::depth_sensor();
// set depth unit
depthSensor.set_option(RS2_OPTION_DEPTH_UNITS, 0.0001); // 0.0001

[ywjia]

thanks. I understood it now. the key is to apply set_option() before starting the pipeline.

issue closed.