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# Rotated Object Detection Pipeline Tutorial
## 1. Introduction to the Rotated Object Detection Pipeline
Rotated object detection is a variant of the object detection module, specifically designed for detecting rotated objects. Rotated bounding boxes are often used to detect rectangular boxes with angular information, where the width and height of the box are no longer parallel to the image coordinate axes. Compared to horizontal rectangular boxes, rotated rectangular boxes generally include less background information. Rotated object detection has important applications in remote sensing scenarios. This pipeline also provides flexible service deployment options, supporting multiple programming languages on various hardware. Moreover, this pipeline offers custom development capabilities, allowing you to train and fine-tune models on your own dataset, with seamless integration of the trained models.
The rotated object detection pipeline includes a rotated object detection module, which contains multiple models. You can choose the model based on the benchmark data provided below.
If you prioritize model accuracy, choose a model with higher accuracy; if you care more about inference speed, choose a model with faster inference speed; if you are concerned about model storage size, choose a model with a smaller storage size.
| Parameter |
Description |
Type |
Options |
Default Value |
input |
Data to be predicted, supporting multiple input types (required). |
Python Var|str|list |
- Python Var: Image data represented by
numpy.ndarray
- str: Local path of image or PDF file, e.g.,
/root/data/img.jpg; URL link, e.g., network URL of image or PDF file: Example; Local directory, the directory should contain images to be predicted, e.g., local path: /root/data/ (currently does not support prediction of PDF files in directories; PDF files must be specified with a specific file path)
- List: Elements of the list must be of the above types, e.g.,
[numpy.ndarray, numpy.ndarray], [\"/root/data/img1.jpg\", \"/root/data/img2.jpg\"], [\"/root/data1\", \"/root/data2\"]
|
None |
device |
The device used for pipeline inference |
str|None |
- CPU: e.g.,
cpu indicates using CPU for inference;
- GPU: e.g.,
gpu:0 indicates using the 1st GPU for inference;
- NPU: e.g.,
npu:0 indicates using the 1st NPU for inference;
- XPU: e.g.,
xpu:0 indicates using the 1st XPU for inference;
- MLU: e.g.,
mlu:0 indicates using the 1st MLU for inference;
- DCU: e.g.,
dcu:0 indicates using the 1st DCU for inference;
- None: If set to
None, the default value initialized by the pipeline will be used. During initialization, the local GPU 0 will be prioritized; if unavailable, the CPU will be used;
|
None |
threshold |
Filtering threshold for low-confidence object |
None|float|dict[int, float] |
- None: If set to
None, the default pipeline initialization parameter 0.5 will be used, i.e., 0.5 as the low-score object filtering threshold for all categories
- float: Any float number greater than 0 and less than 1
- dict[int, float]: The key represents the category ID, and the value represents the threshold for that category, allowing different low-score filtering thresholds for different categories, e.g.,
{0:0.5, 1:0.35} indicates using 0.5 and 0.35 as the low-score filtering thresholds for categories 0 and 1, respectively
|
None |
(3) Process the prediction results. The prediction result for each sample is of the `dict` type and supports operations such as printing, saving as an image, and saving as a `json` file:
| Method |
Description |
Parameter |
Parameter Type |
Parameter Description |
Default Value |
print() |
Print the result to the terminal |
format_json |
bool |
Whether to format the output content using JSON indentation |
True |
indent |
int |
Specify the indentation level to beautify the output JSON data, making it more readable. Effective only when format_json is True |
4 |
ensure_ascii |
bool |
Control whether to escape non-ASCII characters to Unicode. When set to True, all non-ASCII characters will be escaped; False will retain the original characters. Effective only when format_json is True |
False |
save_to_json() |
Save the result as a JSON file |
save_path |
str |
Path to save the file. When it is a directory, the saved file name is consistent with the input file type naming |
None |
indent |
int |
Specify the indentation level to beautify the output JSON data, making it more readable. Effective only when format_json is True |
4 |
ensure_ascii |
bool |
Control whether to escape non-ASCII characters to Unicode. When set to True, all non-ASCII characters will be escaped; False will retain the original characters. Effective only when format_json is True |
False |
save_to_img() |
Save the result as an image file |
save_path |
str |
Path to save the file, supports directory or file path |
None |
- Calling the `print()` method will print the result to the terminal, with the printed content explained as follows:
- `input_path`: `(str)` The input path of the image to be predicted
- `page_index`: `(Union[int, None])` If the input is a PDF file, it indicates which page of the PDF it is, otherwise it is `None`
- `boxes`: `(list)` Detection box information, each element is a dictionary containing the following fields
- `cls_id`: `(int)` Category ID
- `label`: `(str)` Category name
- `score`: `(float)` Confidence score
- `coordinates`: `(list)` Detection box coordinates, in the format `[x1, y1, x2, y2, x3, y3, x4, y4]`
- Calling the `save_to_json()` method will save the above content to the specified `save_path`. If specified as a directory, the saved path will be `save_path/{your_img_basename}_res.json`; if specified as a file, it will be saved directly to that file. Since JSON files do not support saving numpy arrays, the `numpy.array` types will be converted to lists.
- Calling the `save_to_img()` method will save the visualization results to the specified `save_path`. If specified as a directory, the saved path will be `save_path/{your_img_basename}_res.{your_img_extension}`; if specified as a file, it will be saved directly to that file.
* Additionally, it also supports obtaining visualized images and prediction results through attributes, as follows:
API Reference
For the main operations provided by the service:
- The HTTP request method is POST.
- Both the request body and response body are JSON data (JSON objects).
- When the request is processed successfully, the response status code is
200, and the response body has the following properties:
| Name |
Type |
Description |
logId |
string |
The UUID of the request. |
errorCode |
integer |
Error code. Fixed to 0. |
errorMsg |
string |
Error message. Fixed to "Success". |
result |
object |
Operation result. |
- When the request is not processed successfully, the response body has the following properties:
| Name |
Type |
Description |
logId |
string |
The UUID of the request. |
errorCode |
integer |
Error code. Same as the response status code. |
errorMsg |
string |
Error message. |
The main operations provided by the service are as follows:
Perform object detection on the image.
POST /rotated-object-detection
- The request body has the following properties:
| Name |
Type |
Description |
Required |
image |
string |
The URL of an image file accessible to the server or the Base64 encoded result of the image file content. |
Yes |
detThreshold |
number | null |
Please refer to the description of the det_threshold parameter of the pipeline object's predict method. |
No |
clsThreshold |
number | array | object | null |
Please refer to the description of the cls_threshold parameter of the pipeline object's predict method. |
No |
- When the request is processed successfully, the
result property of the response body has the following properties:
| Name |
Type |
Description |
detectedObjects |
array |
Information about the position, category, etc., of the objects. |
image |
string |
Object detection result image. The image is in JPEG format and encoded using Base64. |
Each element in detectedObjects is an object with the following properties:
| Name |
Type |
Description |
bbox |
array |
Object position. The elements in the array are the x-coordinate of the top-left corner, y-coordinate of the top-left corner, x-coordinate of the bottom-right corner, and y-coordinate of the bottom-right corner of the bounding box. |
categoryId |
integer |
Object category ID. |
categoryName |
string |
The name of the target category. |
score |
number |
Object score. |
An example of the result is as follows:
{
"detectedObjects": [
{
"bbox": [
92.88687133789062,
763.1569213867188,
85.16312408447266,
749.5867919921875,
116.07975006103516,
731.994140625,
123.80349731445312,
745.5642700195312
],
"categoryId": 0,
"score": 0.7418514490127563
},
{
"bbox": [
348.2331848144531,
177.5597381591797,
332.77703857421875,
150.24972534179688,
345.2182922363281,
143.2102813720703,
360.6744384765625,
170.52029418945312
],
"categoryId": 1,
"score": 0.7328268885612488
}
],
"image": "xxxxxx"
}
Multi-language Service Invocation Example
Python
import base64
import requests
API_URL = "http://localhost:8080/rotated-object-detection" # Service URL
image_path = "./demo.jpg"
output_image_path = "./out.jpg"
# Encode the local image with Base64
with open(image_path, "rb") as file:
image_bytes = file.read()
image_data = base64.b64encode(image_bytes).decode("ascii")
payload = {"image": image_data} # Base64-encoded file content or image URL
# Call the API
response = requests.post(API_URL, json=payload)
# Process the returned data from the interface
assert response.status_code == 200
result = response.json()["result"]
with open(output_image_path, "wb") as file:
file.write(base64.b64decode(result["image"]))
print(f"Output image saved at {output_image_path}")
print("\nDetected objects:")
print(result["detectedObjects"])
C++
#include <iostream>
#include "cpp-httplib/httplib.h" // https://github.com/Huiyicc/cpp-httplib
#include "nlohmann/json.hpp" // https://github.com/nlohmann/json
#include "base64.hpp" // https://github.com/tobiaslocker/base64
int main() {
httplib::Client client("localhost:8080");
const std::string imagePath = "./demo.jpg";
const std::string outputImagePath = "./out.jpg";
httplib::Headers headers = {
{"Content-Type", "application/json"}
};
// Encode the local image with Base64
std::ifstream file(imagePath, std::ios::binary | std::ios::ate);
std::streamsize size = file.tellg();
file.seekg(0, std::ios::beg);
std::vector<char> buffer(size);
if (!file.read(buffer.data(), size)) {
std::cerr << "Error reading file." << std::endl;
return 1;
}
std::string bufferStr(reinterpret_cast<const char*>(buffer.data()), buffer.size());
std::string encodedImage = base64::to_base64(bufferStr);
nlohmann::json jsonObj;
jsonObj["image"] = encodedImage;
std::string body = jsonObj.dump();
// Call the API
auto response = client.Post("/small-object-detection", headers, body, "application/json");
// Process the returned data from the interface
if (response && response->status == 200) {
nlohmann::json jsonResponse = nlohmann::json::parse(response->body);
auto result = jsonResponse["result"];
encodedImage = result["image"];
std::string decodedString = base64::from_base64(encodedImage);
std::vector<unsigned char> decodedImage(decodedString.begin(), decodedString.end());
std::ofstream outputImage(outPutImagePath, std::ios::binary | std::ios::out);
if (outputImage.is_open()) {
outputImage.write(reinterpret_cast<char*>(decodedImage.data()), decodedImage.size());
outputImage.close();
std::cout << "Output image saved at " << outPutImagePath << std::endl;
} else {
std::cerr << "Unable to open file for writing: " << outPutImagePath << std::endl;
}
auto detectedObjects = result["detectedObjects"];
std::cout << "\nDetected objects:" << std::endl;
for (const auto& category : detectedObjects) {
std::cout << category << std::endl;
}
} else {
std::cout << "Failed to send HTTP request." << std::endl;
return 1;
}
return 0;
}
Java
import okhttp3.*;
import com.fasterxml.jackson.databind.ObjectMapper;
import com.fasterxml.jackson.databind.JsonNode;
import com.fasterxml.jackson.databind.node.ObjectNode;
import java.io.File;
import java.io.FileOutputStream;
import java.io.IOException;
import java.util.Base64;
public class Main {
public static void main(String[] args) throws IOException {
String API_URL = "http://localhost:8080/small-object-detection"; // Service URL
String imagePath = "./demo.jpg"; // Local image
String outputImagePath = "./out.jpg"; // Output image
// Encode the local image using Base64
File file = new File(imagePath);
byte[] fileContent = java.nio.file.Files.readAllBytes(file.toPath());
String imageData = Base64.getEncoder().encodeToString(fileContent);
ObjectMapper objectMapper = new ObjectMapper();
ObjectNode params = objectMapper.createObjectNode();
params.put("image", imageData); // Base64-encoded file content or image URL
// Create an OkHttpClient instance
OkHttpClient client = new OkHttpClient();
MediaType JSON = MediaType.Companion.get("application/json; charset=utf-8");
RequestBody body = RequestBody.Companion.create(params.toString(), JSON);
Request request = new Request.Builder()
.url(API_URL)
.post(body)
.build();
// Call the API and process the response data
try (Response response = client.newCall(request).execute()) {
if (response.isSuccessful()) {
String responseBody = response.body().string();
JsonNode resultNode = objectMapper.readTree(responseBody);
JsonNode result = resultNode.get("result");
String base64Image = result.get("image").asText();
JsonNode detectedObjects = result.get("detectedObjects");
byte[] imageBytes = Base64.getDecoder().decode(base64Image);
try (FileOutputStream fos = new FileOutputStream(outputImagePath)) {
fos.write(imageBytes);
}
System.out.println("Output image saved at " + outputImagePath);
System.out.println("\nDetected objects: " + detectedObjects.toString());
} else {
System.err.println("Request failed with code: " + response.code());
}
}
}
}
Go
package main
import (
"bytes"
"encoding/base64"
"encoding/json"
"fmt"
"io/ioutil"
"net/http"
)
func main() {
API_URL := "http://localhost:8080/small-object-detection"
imagePath := "./demo.jpg"
outputImagePath := "./out.jpg"
// Encode the local image using Base64
imageBytes, err := ioutil.ReadFile(imagePath)
if err != nil {
fmt.Println("Error reading image file:", err)
return
}
imageData := base64.StdEncoding.EncodeToString(imageBytes)
payload := map[string]string{"image": imageData} // Base64-encoded file content or image URL
payloadBytes, err := json.Marshal(payload)
if err != nil {
fmt.Println("Error marshaling payload:", err)
return
}
// Call the API
client := &http.Client{}
req, err := http.NewRequest("POST", API_URL, bytes.NewBuffer(payloadBytes))
if err != nil {
fmt.Println("Error creating request:", err)
return
}
res, err := client.Do(req)
if err != nil {
fmt.Println("Error sending request:", err)
return
}
defer res.Body.Close()
// Process the response data
body, err := ioutil.ReadAll(res.Body)
if err != nil {
fmt.Println("Error reading response body:", err)
return
}
type Response struct {
Result struct {
Image string `json:"image"`
DetectedObjects []map[string]interface{} `json:"detectedObjects"`
} `json:"result"`
}
var respData Response
err = json.Unmarshal([]byte(string(body)), &respData)
if err != nil {
fmt.Println("Error unmarshaling response body:", err)
return
}
outputImageData, err := base64.StdEncoding.DecodeString(respData.Result.Image)
if err != nil {
fmt.Println("Error decoding base64 image data:", err)
return
}
err = ioutil.WriteFile(outputImagePath, outputImageData, 0644)
if err != nil {
fmt.Println("Error writing image to file:", err)
return
}
fmt.Printf("Image saved at %s.jpg\n", outputImagePath)
fmt.Println("\nDetected objects:")
for _, category := range respData.Result.DetectedObjects {
fmt.Println(category)
}
}
C#
using System;
using System.IO;
using System.Net.Http;
using System.Net.Http.Headers;
using System.Text;
using System.Threading.Tasks;
using Newtonsoft.Json.Linq;
class Program
{
static readonly string API_URL = "http://localhost:8080/small-object-detection";
static readonly string imagePath = "./demo.jpg";
static readonly string outputImagePath = "./out.jpg";
static async Task Main(string[] args)
{
var httpClient = new HttpClient();
// Encode the local image in Base64
byte[] imageBytes = File.ReadAllBytes(imagePath);
string image_data = Convert.ToBase64String(imageBytes);
var payload = new JObject{ { "image", image_data } }; // Base64-encoded file content or image URL
var content = new StringContent(payload.ToString(), Encoding.UTF8, "application/json");
// Call the API
HttpResponseMessage response = await httpClient.PostAsync(API_URL, content);
response.EnsureSuccessStatusCode();
// Process the response data
string responseBody = await response.Content.ReadAsStringAsync();
JObject jsonResponse = JObject.Parse(responseBody);
string base64Image = jsonResponse["result"]["image"].ToString();
byte[] outputImageBytes = Convert.FromBase64String(base64Image);
File.WriteAllBytes(outputImagePath, outputImageBytes);
Console.WriteLine($"Output image saved at {outputImagePath}");
Console.WriteLine("\nDetected objects:");
Console.WriteLine(jsonResponse["result"]["detectedObjects"].ToString());
}
}
Node.js
const axios = require('axios');
const fs = require('fs');
const API_URL = 'http://localhost:8080/small-object-detection';
const imagePath = './demo.jpg';
const outputImagePath = "./out.jpg";
let config = {
method: 'POST',
maxBodyLength: Infinity,
url: API_URL,
data: JSON.stringify({
'image': encodeImageToBase64(imagePath) // Base64-encoded file content or image URL
})
};
// Encode the local image in Base64
function encodeImageToBase64(filePath) {
const bitmap = fs.readFileSync(filePath);
return Buffer.from(bitmap).toString('base64');
}
// Call the API
axios.request(config)
.then((response) => {
// Process the response data
const result = response.data["result"];
const imageBuffer = Buffer.from(result["image"], 'base64');
fs.writeFile(outputImagePath, imageBuffer, (err) => {
if (err) throw err;
console.log(`Output image saved at ${outputImagePath}`);
});
console.log("\nDetected objects:");
console.log(result["detectedObjects"]);
})
.catch((error) => {
console.log(error);
});
PHP
<?php
$API_URL = "http://localhost:8080/small-object-detection"; // Service URL
$image_path = "./demo.jpg";
$output_image_path = "./out.jpg";
// Encode the local image in Base64
$image_data = base64_encode(file_get_contents($image_path));
$payload = array("image" => $image_data); // Base64-encoded file content or image URL
// Call the API
$ch = curl_init($API_URL);
curl_setopt($ch, CURLOPT_POST, true);
curl_setopt($ch, CURLOPT_POSTFIELDS, json_encode($payload));
curl_setopt($ch, CURLOPT_HTTPHEADER, array('Content-Type: application/json'));
curl_setopt($ch, CURLOPT_RETURNTRANSFER, true);
$response = curl_exec($ch);
curl_close($ch);
// Process the response data from the API
$result = json_decode($response, true)["result"];
file_put_contents($output_image_path, base64_decode($result["image"]));
echo "Output image saved at " . $output_image_path . "\n";
echo "\nDetected objects:\n";
print_r($result["detectedObjects"]);
?>