NGSIM-US-101-trajectory-dataset-smoothing:使用Savitzky-Golay滤波器平滑N...

# Smoothed Dataset ### Description Here you can find the smoothed dataset in CSV format. We provide two version of the smoothed dataset. Each is smoothed using a different smoothing window. The Savitzky-Golay filter requires a **smoothing window** which dictates the number of points used to smooth a current data point. ### Table of Content 1. [Description](#Description) 2. [Smoothing Window](#File-Structure) 3. [Folder Structure](#Folder-Structure) 4. [File Structure](#Smoothing-Window) ### Smoothing Window We use separately a window of 11 and a window of 21. We specifically chose 11 and 21 because they represent, respectively, 10 and 20 data points excluding the target data point. This in turn corresponds, respectively, to 1 second and 2 seconds of trajectory data respectively. In other words, we use the trajectory data of 1 seconds and 2 seconds to smooth the data. Both datasets can be found in the folder window-11 and window-21 respectively. **NOTE.** the filter is applied to the Local_X and Local_Y and not the Global_X and Global_Y values since they are based on the california state plane coordinate system. Below is a figure dipicting the original and the smoothed trajectory, using smoothing window 11, for the Vehicle with ID 2  Below is a figure dipicting the original and the smoothed trajectory, using smoothing window 21, for the Vehicle with ID 2 trajectory is smother than the previous one.  ### Folder Structure Each folder contains three main files: 1. 0750_0805_us101_smoothed_*_.zip 2. 0805_0820_us101_smoothed_*_.zip 3. 0820_0835_us101_smoothed_*_.zip where * is the value set for the smoothing window. Each file contains all the smoothed vehicle trajectories for the following times respectively 7:50 am - 8:05 am, 8:05 am - 8:20 am, 8:20 am - 8:35 am In addition, you can find three plot images displaying x & y, accelration and velocity before and after smoothing for a sample car from the dataset. ### File Structure Each file is structured in CSV format i.e. in comma separated values. The columns are ordered in the same manner as the original non-smoothed dataset. Nevertheless for reference and ease of use we rewrite the description of the original dataset here. Each column is described in order of appearance: * **Vehicle_ID** Vehicle identification number * **Frame_ID** Frame Identification number * **Total_Frames** Total number of frames in which the vehicle appears in this data set * **Global_Time** Elapsed time in milliseconds since Jan 1, 1970. * **Local_X Lateral** (X) coordinate of the front center of the vehicle in feet with respect to the left-most edge of the section in the direction of travel * **Local_Y** Longitudinal (Y) coordinate of the front center of the vehicle in feet with respect to the entry edge of the section in the direction of travel * **Global_X** of the front center of the vehicle in feet based on the coordinate CA State Plane III in NAD83 * **Global_Y** Y Coordinate of the front center of the vehicle in feet based on the coordinate CA State Plane III in NAD83 * **v_Length** Length of vehicle in feet * **v_Width** Width of vehicle in feet * **v_Class** Vehicle type: 1 - motorcycle, 2 - auto, 3 - truck * **v_Vel** Instantaneous velocity of vehicle in feet/second * **v_Acc** Instantaneous acceleration of vehicle in feet/second square * **Lane_ID** Current lane position of vehicle. Lane 1 is farthest left lane; lane 5 is farthest right lane. Lane 6 is the auxiliary lane between Ventura Boulevard on-ramp and the Cahuenga Boulevard off-ramp. Lane 7 is the on-ramp at Ventura Boulevard, and Lane 8 is the off-ramp at Cahuenga Boulevard * **Preceding** Vehicle ID of the lead vehicle in the same lane. A value of '0' represents no preceding vehicle - occurs at the end of the study section and off-ramp due to the fact that only complete trajectories were recorded by this data collection effort * **Following** Vehicle ID of the vehicle following the subject vehicle in the same lane. A value of '0' represents no following vehicle - occurs at the beginning of the study section and on ramp due to the fact that only complete trajectories were recorded by this data collection effort * **Space_Headway** Space Headway in feet. Spacing provides the distance between the front-center of a vehicle to the front-center of the preceding vehicle. * **Time_Headway** Time Headway provides the time in seconds needed to travel from the front-center of a vehicle (at the speed of the vehicle) to the front-center of the preceding vehicle. A headway value of 9999.99 means that the vehicle is traveling at zero speed (congested conditions).