topic Re: Help mapping color to point in Items with no label

Help mapping color to point

idata — Tue, 20 Mar 2018 04:51:28 GMT

Hello everyone,

This has been asked before, and I believe I am doing the right steps but cannot get it work. I am trying to upgrade from RealSense to RealSense2 using SR300 camera. I am trying to abstract getting a point cloud with color (x, y, z, r, g, b) for other uses. I am trying to map the color to the depth points as follows:

Camera() : pipe(), pipeProfile(), depthScale(0) {

rs2::config cameraConfig;

cameraConfig.enable_stream(RS2_STREAM_DEPTH, 640, 480, RS2_FORMAT_Z16);

cameraConfig.enable_stream(RS2_STREAM_COLOR, 640, 480, RS2_FORMAT_RGB8);

pipeProfile = pipe.start(cameraConfig);

depthScale = pipeProfile.get_device().first().get_depth_scale();

}

void Camera::getCapture() {

rs2::frameset frames = pipe.wait_for_frames();

rs2::depth_frame depthFrame = frames.get_depth_frame();

rs2::video_frame colorFrame = frames.get_color_frame();

rs2_intrinsics depth_intrinsic = depthFrame.get_profile().as().get_intrinsics();

rs2_intrinsics color_intrinsic = colorFrame.get_profile().as().get_intrinsics();

rs2_extrinsics depth_to_color = depthFrame.get_profile().get_extrinsics_to(colorFrame.get_profile());

const uint16_t* depthImage = (const uint16_t*)depthFrame.get_data();

const unsigned char* colorImage = (const unsigned char*)colorFrame.get_data();

for (int dy = 0; dy < depth_intrinsic.height; dy++) {

for (int dx = 0; dx < depth_intrinsic.width; dx++) {

// get depth value at dy, dx

unsigned int i = dy * depth_intrinsic.width + dx;

uint16_t depth_value = depthImage[i];

// if the depth value is 0, we ignore this points.

if (depth_value == 0) {

continue;

}

float depth_in_meters = depth_value * depthScale;

// map the pixel coordinate in depth image to pixel coordinate in color image

float depth_pixel[2] = {(float)dx - 0.5f, (float)dy - 0.5f};

float depth_point[3], color_point[3], color_pixel[2];

rs2_deproject_pixel_to_point(depth_point, &depth_intrinsic, depth_pixel, depth_in_meters);

// if it's out of acceptable range, skip it

if (depth_point[2] > maxAcceptDistance) {

continue;

}

rs2_transform_point_to_point(color_point, &depth_to_color, depth_point);

rs2_project_point_to_pixel(color_pixel, &color_intrinsic, color_point);

// get closest color pixel obtained from calculations and use as the point's color, or white if ouside color image

const int cx = static_cast(color_pixel[0] + 0.5f);

const int cy = static_cast(color_pixel[1] + 0.5f);

// if outside intrinsic parameters, skip the point

if (cx < 0 || cy < 0 || cx > color_intrinsic.width || cy > color_intrinsic.height) {

continue;

}

const unsigned char* offset = static_cast(colorImage + (cy * color_intrinsic.width + cx) * 3);

float x = -1 * depth_point[0];

float y = -1 * depth_point[1];

float z = depth_point[2];

unsigned char r = *(offset);

unsigned char g = *(offset + 1);

unsigned char b = *(offset + 2);

}

I only left the redundant parts. Basically, in the end, (r, g, b) are 0 (or they appear black in the image). Any suggestions?

PS. (Code editor is weird).

Re: Help mapping color to point

MartyG — Tue, 20 Mar 2018 08:31:05 GMT

Have you seen the SDK 2.0 example for creating a point cloud?

https://github.com/IntelRealSense/librealsense/tree/master/examples/pointcloud librealsense/examples/pointcloud at master · IntelRealSense/librealsense · GitHub

Re: Help mapping color to point

idata — Tue, 20 Mar 2018 14:37:02 GMT

Hello MartyG,

I did see the example, but I couldn't figure out how to use the (u, v) values to obtain the (r, g, b) values from the color frame. Any help with that? Thanks.

Re: Help mapping color to point

MartyG — Tue, 20 Mar 2018 14:39:59 GMT

I'll link RealSense stream programming expert jb455 into this discussion to seek his wide knowledge on the subject.

Re: Help mapping color to point

idata — Tue, 20 Mar 2018 16:30:07 GMT

So I know that once you do

rs2::pointcloud pc;

rs2::points points;

rs2::frameset frames = pipe.wait_for_frames();

rs2::depth_frame depth = frames.get_depth_frame();

rs2::video_frame color_frame = frames.get_color_frame();

points = pc.calculate(depth);

pc.map_to(color_frame);

Then, you can get the texture coordinates that correspond to each vertex:

const rs2::vertex* ptr = points.get_vertices();

const rs2::texture_coordinate* tex_coords = points.get_texture_coordinates();

const unsigned char* colorStream = static_cast(color_frame.get_data());

Each texture coordinate has (u, v) value which ranges from [0-1] that can be mapped to the color frame. I did this:

int x = tex_coords[i].u * color_intrinsic.width;

int y = tex_coords[i].v * color_intrinsic.height;

int colorLocation = y * color_intrinsic.width + x;

unsigned char color[3] = {colorStream[colorLocation], colorStream[colorLocation +1], colorStream[colorLocation +2]};

However, everything comes back as a single color. I stepped through and it seems both u and v are always 0.

Re: Help mapping color to point

idata — Thu, 29 Mar 2018 14:59:05 GMT

For anyone that may read this, I had to swap the map_to and calculate statements. However, you also need to get some captures. do as follows:

rs2::pointcloud pc;

rs2::points points;

for (int i = 0; i < 10; i++) pipe.wait_for_frames();

rs2::frameset frames = pipe.wait_for_frames();

rs2::depth_frame depth = frames.get_depth_frame();

rs2::video_frame color_frame = frames.get_color_frame();

pc.map_to(color_frame);

points = pc.calculate(depth);

int width = color_frame.get_width();

int height = color_frame.get_height();

const rs2::vertex* ptr = points.get_vertices();

const rs2::texture_coordinate* tex_coords = points.get_texture_coordinates();

const unsigned char* colorStream = static_cast<</span>const unsigned char*>(color_frame.get_data());

for (int i = 0; i < points.size(); i++) {

int x = static_cast(textureCoordinates[i].u * width);

int y = static_cast(textureCoordinates[i].v * height);

if (y < 0 || y >= height) {

continue;

}

if (x < 0 || x >= width) {

continue;

}

if (rs_vertices[i].z <= 0 || rs_vertices[i].z > maxAcceptDistance) { // Rule out values further than this value

continue;

}

int colorLocation = (y * width + x) * 3;

unsigned char color[3] = {colorData[colorLocation], colorData[colorLocation +1], colorData[colorLocation +2]}; // RGB

float coordinates[3] = { ptr[i].x, ptr[i].y, ptr[i].z };

}