# Depth Preview

This example shows how to set the SGBM (semi-global-matching) disparity-depth node, connects over XLink to transfer the results to
the host real-time, and displays the depth map in OpenCV. Note that disparity is used in this case, as it colorizes in a more
intuitive way. Below is also a preview of using different median filters side-by-side on a depth image. There are 3 depth modes
which you can select inside the code:

 * lr_check: used for better occlusion handling. For more information [click
   here](https://docs.luxonis.com/software/depthai-components/nodes/stereo_depth.md)
 * extended_disparity: suitable for short range objects. For more information [click
   here](https://docs.luxonis.com/software/depthai-components/nodes/stereo_depth.md)
 * subpixel: suitable for long range. For more information [click
   here](https://docs.luxonis.com/software/depthai-components/nodes/stereo_depth.md)

### Similar samples:

 * [RGB Preview](https://docs.luxonis.com/software/depthai/examples/rgb_preview.md)
 * [Mono Preview](https://docs.luxonis.com/software/depthai/examples/mono_preview.md)
 * [Stereo Depth Video](https://docs.luxonis.com/software/depthai/examples/stereo_depth_video.md)

## Demo

Filtering depth using median filter

## Setup

Please run the [install script](https://github.com/luxonis/depthai-python/blob/main/examples/install_requirements.py) to download
all required dependencies. Please note that this script must be ran from git context, so you have to download the
[depthai-python](https://github.com/luxonis/depthai-python) repository first and then run the script

```bash
git clone https://github.com/luxonis/depthai-python.git
cd depthai-python/examples
python3 install_requirements.py
```

For additional information, please follow the [installation guide](https://docs.luxonis.com/software/depthai/manual-install.md).

## Source code

#### Python

```python
#!/usr/bin/env python3

import cv2
import depthai as dai
import numpy as np

# Closer-in minimum depth, disparity range is doubled (from 95 to 190):
extended_disparity = False
# Better accuracy for longer distance, fractional disparity 32-levels:
subpixel = False
# Better handling for occlusions:
lr_check = True

# Create pipeline
pipeline = dai.Pipeline()

# Define sources and outputs
monoLeft = pipeline.create(dai.node.MonoCamera)
monoRight = pipeline.create(dai.node.MonoCamera)
depth = pipeline.create(dai.node.StereoDepth)
xout = pipeline.create(dai.node.XLinkOut)

xout.setStreamName("disparity")

# Properties
monoLeft.setResolution(dai.MonoCameraProperties.SensorResolution.THE_400_P)
monoLeft.setCamera("left")
monoRight.setResolution(dai.MonoCameraProperties.SensorResolution.THE_400_P)
monoRight.setCamera("right")

# Create a node that will produce the depth map (using disparity output as it's easier to visualize depth this way)
depth.setDefaultProfilePreset(dai.node.StereoDepth.PresetMode.HIGH_DENSITY)
# Options: MEDIAN_OFF, KERNEL_3x3, KERNEL_5x5, KERNEL_7x7 (default)
depth.initialConfig.setMedianFilter(dai.MedianFilter.KERNEL_7x7)
depth.setLeftRightCheck(lr_check)
depth.setExtendedDisparity(extended_disparity)
depth.setSubpixel(subpixel)

# Linking
monoLeft.out.link(depth.left)
monoRight.out.link(depth.right)
depth.disparity.link(xout.input)

# Connect to device and start pipeline
with dai.Device(pipeline) as device:

    # Output queue will be used to get the disparity frames from the outputs defined above
    q = device.getOutputQueue(name="disparity", maxSize=4, blocking=False)

    while True:
        inDisparity = q.get()  # blocking call, will wait until a new data has arrived
        frame = inDisparity.getFrame()
        # Normalization for better visualization
        frame = (frame * (255 / depth.initialConfig.getMaxDisparity())).astype(np.uint8)

        cv2.imshow("disparity", frame)

        # Available color maps: https://docs.opencv.org/3.4/d3/d50/group__imgproc__colormap.html
        frame = cv2.applyColorMap(frame, cv2.COLORMAP_JET)
        cv2.imshow("disparity_color", frame)

        if cv2.waitKey(1) == ord('q'):
            break
```

#### C++

```cpp
#include <iostream>

// Includes common necessary includes for development using depthai library
#include "depthai/depthai.hpp"

// Closer-in minimum depth, disparity range is doubled (from 95 to 190):
static std::atomic<bool> extended_disparity{false};
// Better accuracy for longer distance, fractional disparity 32-levels:
static std::atomic<bool> subpixel{false};
// Better handling for occlusions:
static std::atomic<bool> lr_check{true};

int main() {
    // Create pipeline
    dai::Pipeline pipeline;

    // Define sources and outputs
    auto monoLeft = pipeline.create<dai::node::MonoCamera>();
    auto monoRight = pipeline.create<dai::node::MonoCamera>();
    auto depth = pipeline.create<dai::node::StereoDepth>();
    auto xout = pipeline.create<dai::node::XLinkOut>();

    xout->setStreamName("disparity");

    // Properties
    monoLeft->setResolution(dai::MonoCameraProperties::SensorResolution::THE_400_P);
    monoLeft->setCamera("left");
    monoRight->setResolution(dai::MonoCameraProperties::SensorResolution::THE_400_P);
    monoRight->setCamera("right");

    // Create a node that will produce the depth map (using disparity output as it's easier to visualize depth this way)
    depth->setDefaultProfilePreset(dai::node::StereoDepth::PresetMode::HIGH_DENSITY);
    // Options: MEDIAN_OFF, KERNEL_3x3, KERNEL_5x5, KERNEL_7x7 (default)
    depth->initialConfig.setMedianFilter(dai::MedianFilter::KERNEL_7x7);
    depth->setLeftRightCheck(lr_check);
    depth->setExtendedDisparity(extended_disparity);
    depth->setSubpixel(subpixel);

    // Linking
    monoLeft->out.link(depth->left);
    monoRight->out.link(depth->right);
    depth->disparity.link(xout->input);

    // Connect to device and start pipeline
    dai::Device device(pipeline);

    // Output queue will be used to get the disparity frames from the outputs defined above
    auto q = device.getOutputQueue("disparity", 4, false);

    while(true) {
        auto inDepth = q->get<dai::ImgFrame>();
        auto frame = inDepth->getFrame();
        // Normalization for better visualization
        frame.convertTo(frame, CV_8UC1, 255 / depth->initialConfig.getMaxDisparity());

        cv::imshow("disparity", frame);

        // Available color maps: https://docs.opencv.org/3.4/d3/d50/group__imgproc__colormap.html
        cv::applyColorMap(frame, frame, cv::COLORMAP_JET);
        cv::imshow("disparity_color", frame);

        int key = cv::waitKey(1);
        if(key == 'q' || key == 'Q') {
            return 0;
        }
    }
    return 0;
}
```

## Pipeline

### examples/depth_preview.pipeline.json

```json
{
  "pipeline": {
    "connections": [
      {
        "node1Id": 0,
        "node1Output": "out",
        "node1OutputGroup": "",
        "node2Id": 2,
        "node2Input": "left",
        "node2InputGroup": ""
      },
      {
        "node1Id": 1,
        "node1Output": "out",
        "node1OutputGroup": "",
        "node2Id": 2,
        "node2Input": "right",
        "node2InputGroup": ""
      },
      {
        "node1Id": 2,
        "node1Output": "disparity",
        "node1OutputGroup": "",
        "node2Id": 3,
        "node2Input": "in",
        "node2InputGroup": ""
      }
    ],
    "globalProperties": {
      "calibData": null,
      "cameraTuningBlobSize": null,
      "cameraTuningBlobUri": "",
      "leonCssFrequencyHz": 700000000.0,
      "leonMssFrequencyHz": 700000000.0,
      "pipelineName": null,
      "pipelineVersion": null,
      "sippBufferSize": 18432,
      "sippDmaBufferSize": 16384,
      "xlinkChunkSize": -1
    },
    "nodes": [
      [
        0,
        {
          "id": 0,
          "ioInfo": [
            [
              [
                "",
                "inputControl"
              ],
              {
                "blocking": true,
                "group": "",
                "id": 1,
                "name": "inputControl",
                "queueSize": 8,
                "type": 3,
                "waitForMessage": false
              }
            ],
            [
              [
                "",
                "out"
              ],
              {
                "blocking": false,
                "group": "",
                "id": 2,
                "name": "out",
                "queueSize": 8,
                "type": 0,
                "waitForMessage": false
              }
            ],
            [
              [
                "",
                "raw"
              ],
              {
                "blocking": false,
                "group": "",
                "id": 3,
                "name": "raw",
                "queueSize": 8,
                "type": 0,
                "waitForMessage": false
              }
            ],
            [
              [
                "",
                "frameEvent"
              ],
              {
                "blocking": false,
                "group": "",
                "id": 4,
                "name": "frameEvent",
                "queueSize": 8,
                "type": 0,
                "waitForMessage": false
              }
            ]
          ],
          "name": "MonoCamera",
          "properties": {
            "boardSocket": -1,
            "cameraName": "left",
            "fps": 30.0,
            "imageOrientation": -1,
            "initialControl": {
              "aeLockMode": false,
              "aeMaxExposureTimeUs": 0,
              "aeRegion": {
                "height": 0,
                "priority": 0,
                "width": 0,
                "x": 0,
                "y": 0
              },
              "afRegion": {
                "height": 0,
                "priority": 0,
                "width": 0,
                "x": 0,
                "y": 0
              },
              "antiBandingMode": 0,
              "autoFocusMode": 3,
              "awbLockMode": false,
              "awbMode": 0,
              "brightness": 0,
              "captureIntent": 0,
              "chromaDenoise": 0,
              "cmdMask": 0,
              "contrast": 0,
              "controlMode": 0,
              "effectMode": 0,
              "expCompensation": 0,
              "expManual": {
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                "frameDurationUs": 0,
                "sensitivityIso": 0
              },
              "frameSyncMode": 0,
              "lensPosAutoInfinity": 0,
              "lensPosAutoMacro": 0,
              "lensPosition": 0,
              "lensPositionRaw": 0.0,
              "lowPowerNumFramesBurst": 0,
              "lowPowerNumFramesDiscard": 0,
              "lumaDenoise": 0,
              "saturation": 0,
              "sceneMode": 0,
              "sharpness": 0,
              "strobeConfig": {
                "activeLevel": 0,
                "enable": 0,
                "gpioNumber": 0
              },
              "strobeTimings": {
                "durationUs": 0,
                "exposureBeginOffsetUs": 0,
                "exposureEndOffsetUs": 0
              },
              "wbColorTemp": 0
            },
            "isp3aFps": 0,
            "numFramesPool": 3,
            "numFramesPoolRaw": 3,
            "rawPacked": null,
            "resolution": 2
          }
        }
      ],
      [
        1,
        {
          "id": 1,
          "ioInfo": [
            [
              [
                "",
                "inputControl"
              ],
              {
                "blocking": true,
                "group": "",
                "id": 5,
                "name": "inputControl",
                "queueSize": 8,
                "type": 3,
                "waitForMessage": false
              }
            ],
            [
              [
                "",
                "out"
              ],
              {
                "blocking": false,
                "group": "",
                "id": 6,
                "name": "out",
                "queueSize": 8,
                "type": 0,
                "waitForMessage": false
              }
            ],
            [
              [
                "",
                "raw"
              ],
              {
                "blocking": false,
                "group": "",
                "id": 7,
                "name": "raw",
                "queueSize": 8,
                "type": 0,
                "waitForMessage": false
              }
            ],
            [
              [
                "",
                "frameEvent"
              ],
              {
                "blocking": false,
                "group": "",
                "id": 8,
                "name": "frameEvent",
                "queueSize": 8,
                "type": 0,
                "waitForMessage": false
              }
            ]
          ],
          "name": "MonoCamera",
          "properties": {
            "boardSocket": -1,
            "cameraName": "right",
            "fps": 30.0,
            "imageOrientation": -1,
            "initialControl": {
              "aeLockMode": false,
              "aeMaxExposureTimeUs": 0,
              "aeRegion": {
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                "priority": 0,
                "width": 0,
                "x": 0,
                "y": 0
              },
              "afRegion": {
                "height": 0,
                "priority": 0,
                "width": 0,
                "x": 0,
                "y": 0
              },
              "antiBandingMode": 0,
              "autoFocusMode": 3,
              "awbLockMode": false,
              "awbMode": 0,
              "brightness": 0,
              "captureIntent": 0,
              "chromaDenoise": 0,
              "cmdMask": 0,
              "contrast": 0,
              "controlMode": 0,
              "effectMode": 0,
              "expCompensation": 0,
              "expManual": {
                "exposureTimeUs": 0,
                "frameDurationUs": 0,
                "sensitivityIso": 0
              },
              "frameSyncMode": 0,
              "lensPosAutoInfinity": 0,
              "lensPosAutoMacro": 0,
              "lensPosition": 0,
              "lensPositionRaw": 0.0,
              "lowPowerNumFramesBurst": 0,
              "lowPowerNumFramesDiscard": 0,
              "lumaDenoise": 0,
              "saturation": 0,
              "sceneMode": 0,
              "sharpness": 0,
              "strobeConfig": {
                "activeLevel": 0,
                "enable": 0,
                "gpioNumber": 0
              },
              "strobeTimings": {
                "durationUs": 0,
                "exposureBeginOffsetUs": 0,
                "exposureEndOffsetUs": 0
              },
              "wbColorTemp": 0
            },
            "isp3aFps": 0,
            "numFramesPool": 3,
            "numFramesPoolRaw": 3,
            "rawPacked": null,
            "resolution": 2
          }
        }
      ],
      [
        2,
        {
          "id": 2,
          "ioInfo": [
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              [
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                "inputConfig"
              ],
              {
                "blocking": false,
                "group": "",
                "id": 9,
                "name": "inputConfig",
                "queueSize": 4,
                "type": 3,
                "waitForMessage": false
              }
            ],
            [
              [
                "",
                "left"
              ],
              {
                "blocking": false,
                "group": "",
                "id": 10,
                "name": "left",
                "queueSize": 8,
                "type": 3,
                "waitForMessage": true
              }
            ],
            [
              [
                "",
                "debugExtDispLrCheckIt1"
              ],
              {
                "blocking": false,
                "group": "",
                "id": 22,
                "name": "debugExtDispLrCheckIt1",
                "queueSize": 8,
                "type": 0,
                "waitForMessage": false
              }
            ],
            [
              [
                "",
                "right"
              ],
              {
                "blocking": false,
                "group": "",
                "id": 11,
                "name": "right",
                "queueSize": 8,
                "type": 3,
                "waitForMessage": true
              }
            ],
            [
              [
                "",
                "syncedLeft"
              ],
              {
                "blocking": false,
                "group": "",
                "id": 12,
                "name": "syncedLeft",
                "queueSize": 8,
                "type": 0,
                "waitForMessage": false
              }
            ],
            [
              [
                "",
                "depth"
              ],
              {
                "blocking": false,
                "group": "",
                "id": 13,
                "name": "depth",
                "queueSize": 8,
                "type": 0,
                "waitForMessage": false
              }
            ],
            [
              [
                "",
                "disparity"
              ],
              {
                "blocking": false,
                "group": "",
                "id": 14,
                "name": "disparity",
                "queueSize": 8,
                "type": 0,
                "waitForMessage": false
              }
            ],
            [
              [
                "",
                "syncedRight"
              ],
              {
                "blocking": false,
                "group": "",
                "id": 15,
                "name": "syncedRight",
                "queueSize": 8,
                "type": 0,
                "waitForMessage": false
              }
            ],
            [
              [
                "",
                "debugDispCostDump"
              ],
              {
                "blocking": false,
                "group": "",
                "id": 20,
                "name": "debugDispCostDump",
                "queueSize": 8,
                "type": 0,
                "waitForMessage": false
              }
            ],
            [
              [
                "",
                "debugDispLrCheckIt2"
              ],
              {
                "blocking": false,
                "group": "",
                "id": 21,
                "name": "debugDispLrCheckIt2",
                "queueSize": 8,
                "type": 0,
                "waitForMessage": false
              }
            ],
            [
              [
                "",
                "rectifiedLeft"
              ],
              {
                "blocking": false,
                "group": "",
                "id": 16,
                "name": "rectifiedLeft",
                "queueSize": 8,
                "type": 0,
                "waitForMessage": false
              }
            ],
            [
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                "",
                "debugExtDispLrCheckIt2"
              ],
              {
                "blocking": false,
                "group": "",
                "id": 23,
                "name": "debugExtDispLrCheckIt2",
                "queueSize": 8,
                "type": 0,
                "waitForMessage": false
              }
            ],
            [
              [
                "",
                "rectifiedRight"
              ],
              {
                "blocking": false,
                "group": "",
                "id": 17,
                "name": "rectifiedRight",
                "queueSize": 8,
                "type": 0,
                "waitForMessage": false
              }
            ],
            [
              [
                "",
                "confidenceMap"
              ],
              {
                "blocking": false,
                "group": "",
                "id": 24,
                "name": "confidenceMap",
                "queueSize": 8,
                "type": 0,
                "waitForMessage": false
              }
            ],
            [
              [
                "",
                "outConfig"
              ],
              {
                "blocking": false,
                "group": "",
                "id": 18,
                "name": "outConfig",
                "queueSize": 8,
                "type": 0,
                "waitForMessage": false
              }
            ],
            [
              [
                "",
                "debugDispLrCheckIt1"
              ],
              {
                "blocking": false,
                "group": "",
                "id": 19,
                "name": "debugDispLrCheckIt1",
                "queueSize": 8,
                "type": 0,
                "waitForMessage": false
              }
            ]
          ],
          "name": "StereoDepth",
          "properties": {
            "alphaScaling": null,
            "baseline": null,
            "depthAlignCamera": -1,
            "depthAlignmentUseSpecTranslation": null,
            "disparityToDepthUseSpecTranslation": null,
            "enableRectification": true,
            "enableRuntimeStereoModeSwitch": false,
            "focalLength": null,
            "focalLengthFromCalibration": true,
            "height": null,
            "initialConfig": {
              "algorithmControl": {
                "centerAlignmentShiftFactor": null,
                "customDepthUnitMultiplier": 1000.0,
                "depthAlign": 0,
                "depthUnit": 2,
                "disparityShift": 0,
                "enableExtended": false,
                "enableLeftRightCheck": true,
                "enableSubpixel": false,
                "leftRightCheckThreshold": 10,
                "numInvalidateEdgePixels": 0,
                "subpixelFractionalBits": 3
              },
              "censusTransform": {
                "enableMeanMode": true,
                "kernelMask": 0,
                "kernelSize": -1,
                "threshold": 0
              },
              "costAggregation": {
                "divisionFactor": 1,
                "horizontalPenaltyCostP1": 250,
                "horizontalPenaltyCostP2": 500,
                "verticalPenaltyCostP1": 250,
                "verticalPenaltyCostP2": 500
              },
              "costMatching": {
                "confidenceThreshold": 245,
                "disparityWidth": 1,
                "enableCompanding": false,
                "invalidDisparityValue": 0,
                "linearEquationParameters": {
                  "alpha": 0,
                  "beta": 2,
                  "threshold": 127
                }
              },
              "postProcessing": {
                "bilateralSigmaValue": 0,
                "brightnessFilter": {
                  "maxBrightness": 256,
                  "minBrightness": 0
                },
                "decimationFilter": {
                  "decimationFactor": 1,
                  "decimationMode": 0
                },
                "median": 7,
                "spatialFilter": {
                  "alpha": 0.5,
                  "delta": 0,
                  "enable": false,
                  "holeFillingRadius": 2,
                  "numIterations": 1
                },
                "speckleFilter": {
                  "enable": false,
                  "speckleRange": 50
                },
                "temporalFilter": {
                  "alpha": 0.4000000059604645,
                  "delta": 0,
                  "enable": false,
                  "persistencyMode": 3
                },
                "thresholdFilter": {
                  "maxRange": 65535,
                  "minRange": 0
                }
              }
            },
            "mesh": {
              "meshLeftUri": "",
              "meshRightUri": "",
              "meshSize": null,
              "stepHeight": 16,
              "stepWidth": 16
            },
            "numFramesPool": 3,
            "numPostProcessingMemorySlices": -1,
            "numPostProcessingShaves": -1,
            "outHeight": null,
            "outKeepAspectRatio": true,
            "outWidth": null,
            "rectificationUseSpecTranslation": null,
            "rectifyEdgeFillColor": 0,
            "useHomographyRectification": null,
            "width": null
          }
        }
      ],
      [
        3,
        {
          "id": 3,
          "ioInfo": [
            [
              [
                "",
                "in"
              ],
              {
                "blocking": true,
                "group": "",
                "id": 25,
                "name": "in",
                "queueSize": 8,
                "type": 3,
                "waitForMessage": true
              }
            ]
          ],
          "name": "XLinkOut",
          "properties": {
            "maxFpsLimit": -1.0,
            "metadataOnly": false,
            "streamName": "disparity"
          }
        }
      ]
    ]
  }
}
```

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