Hi I successfully saved the depth map to 32-bit binary file. Then I can read the file and convert it to png using python opencv.
func convertDepthData(depthMap: CVPixelBuffer) -> [[Float32]] {
let width = CVPixelBufferGetWidth(depthMap)
let height = CVPixelBufferGetHeight(depthMap)
var convertedDepthMap: [[Float32]] = Array(
repeating: Array(repeating: 0, count: width),
count: height
)
CVPixelBufferLockBaseAddress(depthMap, CVPixelBufferLockFlags(rawValue: 2))
let floatBuffer = unsafeBitCast(
CVPixelBufferGetBaseAddress(depthMap),
to: UnsafeMutablePointer<Float32>.self
)
for row in 0 ..< height {
for col in 0 ..< width {
convertedDepthMap[row][col] = floatBuffer[width * row + col]
}
}
CVPixelBufferUnlockBaseAddress(depthMap, CVPixelBufferLockFlags(rawValue: 2))
return convertedDepthMap
}
Then save it to app container.
func saveFloat32ArrayToDocumentsDirectory(array: [[Float32]], fileName: String, folderName: String) -> URL? {
let fileManager = FileManager.default
let datasetDirectory = getDatasetDirectory()
let depthDirectory = datasetDirectory.appendingPathComponent(folderName)
if !FileManager.default.fileExists(atPath: depthDirectory.path) {
do {
try FileManager.default.createDirectory(at: depthDirectory, withIntermediateDirectories: true, attributes: nil)
} catch {
print("Error creating depth directory: \(error.localizedDescription)")
return nil
}
}
let fileURL = depthDirectory.appendingPathComponent(fileName)
let rowCount = array.count
let colCount = array[0].count
var flatArray = array.flatMap { $0 }
do {
let data = Data(bytes: &flatArray, count: MemoryLayout<Float32>.size * rowCount * colCount)
try data.write(to: fileURL, options: .atomic)
return fileURL
} catch {
print("Error saving float32 array: \(error)")
return nil
}
}
You can call these two function in this way, please note that the frame is ARFrame.
guard let depthMap = frame.sceneDepth?.depthMap
let convertedDepthMap = convertDepthData(depthMap: depthMap)
// Save the converted depth map
let fileName = String(format: "%06d.bin", frameNumber)
if let savedFileURL = saveFloat32ArrayToDocumentsDirectory(array: convertedDepthMap, fileName: fileName, folderName: "depth") {
print("Array saved to: \(savedFileURL)")
} else {
print("Error saving float32 array to the app container.")
}
In openCV, you can get the depth array or convert to png. The depth image is 256*192. Because the original value is in float and we can only save int in png, I times 1000. Meanwhile, I save a .bin file to a 16-bit grayscale png.
import numpy as np
import cv2
import glob
import os
from PIL import Image
# Set the number of rows and columns in your 2D Float32 array
row_count = 192
col_count = 256
# Replace this with the path to the folder containing the binary files
folder_path = "./depth/"
output_path = "./depthImg2/"
# Loop through all the .bin files in the folder
for bin_file_path in glob.glob(os.path.join(folder_path, "*.bin")):
# Read the binary file and convert it to a NumPy array
with open(bin_file_path, "rb") as f:
float32_array = np.fromfile(f, dtype=np.float32).reshape(row_count, col_count)
print(float32_array)
float32_array *= 1000
# Normalize the float32 array to the range [0, 2**16 - 1] and convert it to a 16-bit unsigned integer format
# normalized_array = cv2.normalize(float32_array, None, 0, 2**16 - 1, cv2.NORM_MINMAX)
max_depth = np.max(float32_array)
min_depth = np.min(float32_array)
print(f"Max depth: {max_depth}, Min depth: {min_depth}")
uint16_array = float32_array.astype(np.uint16)
# Get the filename without the extension
filename = os.path.splitext(os.path.basename(bin_file_path))[0]
# Save the 16-bit grayscale depth image with the same filename as the original file
depth_image_path = os.path.join(output_path, filename + ".png")
cv2.imwrite(depth_image_path, uint16_array)
