DAÑOS SUJETOS A VIGILANCIA EPIDEMIOLOGICA

The developed method is implemented in Matlab on Windows 64bit. The experiment was benchmarked on an Intel(R) Core(TM) i7-3820 CPU @ 3.60 GHz with 64.0 GB RAM and NVIDIA GeForce GTX 400 graphics card. The Matlab pool is used to enable parallel computation by creating jobs on a pool of workers and connecting the pool to the Matlab client. In the following, we present experimental results on each of our datasets.

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a. Smart Road results

To fairly report the performance on the Smart Road dataset, not only we evaluate the accuracy by the per-pixel classification rate – which is mainly determined by how well we can label the number of asset categories – but also the average of the per-pixel rates over all the asset categories. Figure 4.14 shows examples of the experimental results. As observed, most parts of these video frames are properly segmented and labeled with their corresponding asset categories.

Figure 4.14 Example Results from the Smart Road Testing Dataset

In order to measure the accuracy of recognition on testing images, the outcomes are compared with their corresponding ground truth images. Hence, the color value at each pixel in the segmented imagery is compared with ground truth. The accuracy of segmentation for each category of roadway assets is presented in Table 4.5. The average accuracy is 87.13%.

We also compare our results with those reported in Section 5.1. As shown in Table 4.6, the average accuracy of recognition is increased by 0.38%. This is because mapping geometric labels to semantic labels can increase the accuracy of recognition for asphalt pavement, guardrails, light poles, soil, and pavement marking categories. As reported in Section 5.1 the main confusions for the Semantic Texton Forest method are between asphalt pavement, concrete pavement, and soil categories while adding the geometric information to the semantic context has increased the

(a) Query (b) Labeling

(c) Ground Truth Geometric

Labels (d) Testing Image Geometric

(f) Testing Image Semantic (e) Ground Truth

Semantic Labels

Asphalt Pavement Concrete Pavement Guardrail Pole Tree Pavement Marking Traffic Signal Sky Soil

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accuracy. Our new method also outperforms the computational time for the Semantic Texton Forest method with an order of magnitude, and requires significantly smaller amount of supervision in the training process.

Table 4.5 Accuracy of 2D Video Frame Semantic Segmentation Asset Labels Accuracy (Percent)

Asphalt Pavement 89.29 Concrete Pavement 96.69 Guardrail 88.54 Light Poles 78.36 Traffic Signs 96.61 Trees 76.43 Grass 72.69 Soil 90.4 Sky 96.43 Safety Cones 81.38 Traffic Signals 86.03 Pavement Markings 92.76

Table 4.6 Comparison of Segmentation Accuracy for Superparsing and Semantic Texton Forest Method on Smart Road Dataset

Asset Labels Superparsing STF Difference

Asphalt Pavement 89.29 82.58 +6.71 Concrete Pavement 96.69 99.04 -2.35 Guardrail 88.54 85.81 +2.73 Light Poles 78.36 71.77 +6.59 Traffic Signs 96.61 98.05 -1.44 Trees 76.43 78.62 -2.19 Grass 72.69 72.3 +0.39 Soil 90.4 87.3 +3.1 Sky 96.43 98.25 -1.82 Safety Cones 81.38 85.89 -4.51 Traffic Signals 86.03 91.78 -5.75 Pavement Markings 92.76 89.67 +3.09 Average Accuracy 87.13 86.75 +0.38

Figure 4.15 shows the confusion matrix for segmentation of asset categories. The average accuracy of 79% for asset segmentation is achieved which indicate how accurately each superpixel region is segmented in the video frames. Such average accuracy shows 2.5% better on the performance of the new method compared to Semantic Texton Forest based method which reports

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76.5% on the same testing dataset. The proposed method shows the best performance on traffic signals, safety cones, and guardrails. As it can be observed, the maximum confusion happens between asphalt pavement and concrete pavement asset categories. This is primarily related to the visual consistency of these two categories. This confusion has been decreased due to adding the geometric information to the semantic context with respect to our previous work using Semantic Texton Forest. Some examples of segmentation results of the same images in both Semantic Texton Forest and superparsing method is shown in Figure 4.16.

Figure 4.15 Confusion Matrix on the Smart Road Testing Dataset

b. Interstate I-57 results

The second and more comprehensive dataset in our experiment is the I-57 dataset. Figure 4.17 shows several examples of the experimental results on the segmentation of assets. As observed, most parts of these video frames are properly segmented for the expected assets. The final results on the I-57 dataset achieves a classification rate of 88.24%. In order to measure the accuracy of recognition on both training and testing images, we compare the segmented video frames at the pixel level with their corresponding ground truth. Table 4.7 shows accuracy of recognition on training and testing video frames .The accuracy of segmentation is shown through the confusion matrix for segmentation of asset categories. Overall, an average accuracy of 82.02% for region segmentation is achieved.

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Figure 4.16 Several Examples, Illustrating the Differences Between Superparsing and Semantic Texton Forest Based Methods on the Smart Road Testing Dataset. Although Colors Are Different, All Segmentation Correspond Uniformly Across the Methods

(a) Original Image (b) Superparsing

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Figure 4.17 Results of Segmentation for Both Geometric Labels and Semantic Labels

(a) Query (b) Ground Truth Geometric Labels

(c) Ground Truth Semantic Labels (d) Testing Image

Geometric

(e) Testing Image Semantic 91.7% 89.3% 97.7% 93.0% 88.3% 87.2% 92.3% 84.3% 97.7% 83.2% 98.0% 89.5% 94.1% 77.6% 99.1% 89.9% 96.3% 85.4%

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Table 4.7 Accuracy of Recognition on I-57 Dataset Asset Labels Accuracy (Percent)

Pavement 91.99 Shoulder 93.35 Guardrail 87.17 Pavement Markings 91.22 Light Poles 76.48 Traffic Signs 90.37 Bridges 90.36 Sky 92.52 Others 80.73 Average Accuracy 88.24

Figure 4.18 Confusion Matrix of Segmentation on I-57 Dataset

c. Video parsing

The video segmentation method was tested on the I-57 dataset which includes frames of video streams. There are a total of 550 labeled frames in the dataset with 347 used for training and 203 for testing. Figure 4.19 shows some examples of video parsing results for continuous frames of video stream.

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Figure 4.19 Results of Video Parsing on I-57 Dataset

4.3. Evaluation of Multi-Class Traffic Sign Detection and Classification Methods for U.S. Roadway Asset Inventory Management

4.3.1. Data collection and setup

For evaluating the performance of the multi-class traffic sign detection and classification, the experimental dataset was collected along the US-460 and US Interstate 57 by the State of Illinois’ Department of Transportation. This dataset is used for both training and testing purposes with split of 70 percent for training and 30 percent for testing. This dataset is released publicly through http://raamac.cee.illinois.edu/aca for other researchers to further develop and validate new algorithms.

The dataset contains different categories of traffic signs based on the signs’ message which are annotated manually for training and testing purposes. Training frames are cropped to contain only single traffic sign. In order to create a comprehensive dataset with varying viewpoints, scale, illumination changes, and intra-class variability the videos were collected in different weather condition and on both highway and roadway. To increase negative samples which are needed for training AdaBoost classifier, we also added 16,000 negative samples of typical backgrounds of roadways and highways. The negative images for each binary classification process includes both

Video Frames

Ground Truth Segmentation

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positive examples of other categories of traffic signs and also generic roadway and highway backgrounds. Table 4.8 shows the specification of the training and testing datasets.

Table 4.8 Specification of Our Released Traffic Sign Dataset

Type Color Dataset Positive Negative Sign Message

Warning Yellow Training 1523 6,174 Warning

Testing 653 2,658

Regulatory White, Blue, Green

Training 5924 7,353 Regulatory, Direction (including

mile markers) Testing 2539 3,311

Stop Sign Red Training 164 2,228 Always means Stop

Testing 71 3,240

Yield Red Training 109 2,245 Yield, Slow down,

Prepare to Stop

Testing 48 3,263

To achieve the best performance, we conduct experiments with several spatial scales of (0.75, 1.00, 1.25) of the template spatial resolution and consider a 6.67% shift among observed pixels (i.e., window overlap) to find the best candidates for the traffic signs. The results of different sliding window size for different types of traffic sign has been tested. The 64×64 pixel image patches, as shown in Table 4.9, have the minimum FN rates and maximum FP rates among all other sliding window sizes.

Table 4.9 Specification of Our Released Traffic Sign Dataset

False Negatives Rate False Positives Rate

Scale Factor 0.75 1.00 1.25 0.75 1.00 1.25

Warning 0.06% 0.06% 3.64% 13.68% 14.19% 36.76%

Regulatory 3.67% 2.17% 6.48% 11.19% 19.23% 21.95%

Stop Sign 0.00% 0.00% 9.23% 23.08% 30.77% 23.08%

Yield 0.00% 0.00% 4.49% 14.61% 29.21% 38.20%