app.py

import pandas as pd
import tensorflow as tf
from tensorflow.keras.models import load_model
import cv2
import numpy as np
import matplotlib.pyplot as plt
import gradio as gr

# developing the flowfield space
flow_field = np.ones((128,256), dtype = np.uint8)

# Changing the left input side
flow_field[:,0] = 3
# Changing the right output side
flow_field[:,-1] = 4
# Changing the top layer
flow_field[0,:] = 2
# Changing the bottom layer
flow_field[-1,:] = 2

mean_u = 0.075003795
mean_v = -0.000036
mean_p = 0.004301

std_dev_u = 0.04605
std_dev_v = 0.013812
std_dev_p = 0.007917

def nvs_loss(y_pred, rho=10, nu=0.0001): #arbitary rho and nu(Later use values of air)
      u,v,p = tf.split(y_pred, 3, axis=3)

  #First order derivative
      du_dx, du_dy = tf.image.image_gradients(u) # tf.image.image_gradients returns a tuple containing two tensors: u-grad along the x dir and u-grad along the y dir
      dv_dx, dv_dy = tf.image.image_gradients(v)
      dp_dx, dp_dy = tf.image.image_gradients(p)

  #Second order derivatives
      du_dx2, du_dydx = tf.image.image_gradients(du_dx) # du_dydx will be unused
      du_dxdy, du_dy2 = tf.image.image_gradients(du_dy) # du_dxdy will be unused

      dv_dx2, dv_dydx = tf.image.image_gradients(dv_dx)
      dv_dxdy, dv_dy2 = tf.image.image_gradients(dv_dy)

  #Momentum equation
      er1_tensor = tf.math.multiply(u, du_dx) + tf.math.multiply(v, du_dy) + 1.0*dp_dx/rho - nu*(du_dx2 + du_dy2)
      er2_tensor = tf.math.multiply(u, dv_dx) + tf.math.multiply(v, dv_dy) + 1.0*dp_dy/rho - nu*(dv_dx2 + dv_dy2)

  # # #Continuity equation
      er3_tensor = du_dx + dv_dy

      er1 = tf.reduce_mean(er1_tensor)
      er2 = tf.reduce_mean(er2_tensor)
      er3 = tf.reduce_mean(er3_tensor)

      return  er1*er1 + er2*er2 + er3*er3

 # Initiating the Loss Function-
def custom_loss(y_true, y_pred):
  nv_loss = nvs_loss(y_pred)
  mse_loss = tf.reduce_mean(tf.square(y_true-y_pred))  # Try mse loss function here
  return mse_loss + nv_loss

import torch
import matplotlib
def colorize(value, vmin=None, vmax=None, cmap='gray_r', invalid_val=-99, invalid_mask=None, background_color=(128, 128, 128, 255), gamma_corrected=False, value_transform=None):
    """Converts a depth map to a color image.

    Args:
        value (torch.Tensor, numpy.ndarry): Input depth map. Shape: (H, W) or (1, H, W) or (1, 1, H, W). All singular dimensions are squeezed
        vmin (float, optional): vmin-valued entries are mapped to start color of cmap. If None, value.min() is used. Defaults to None.
        vmax (float, optional):  vmax-valued entries are mapped to end color of cmap. If None, value.max() is used. Defaults to None.
        cmap (str, optional): matplotlib colormap to use. Defaults to 'magma_r'.
        invalid_val (int, optional): Specifies value of invalid pixels that should be colored as 'background_color'. Defaults to -99.
        invalid_mask (numpy.ndarray, optional): Boolean mask for invalid regions. Defaults to None.
        background_color (tuple[int], optional): 4-tuple RGB color to give to invalid pixels. Defaults to (128, 128, 128, 255).
        gamma_corrected (bool, optional): Apply gamma correction to colored image. Defaults to False.
        value_transform (Callable, optional): Apply transform function to valid pixels before coloring. Defaults to None.

    Returns:
        numpy.ndarray, dtype - uint8: Colored depth map. Shape: (H, W, 4)
    """
    if isinstance(value, torch.Tensor):
        value = value.detach().cpu().numpy()

    value = value.squeeze()
    if invalid_mask is None:
        invalid_mask = value == invalid_val
    mask = np.logical_not(invalid_mask)

    # normalize
    # vmin = np.percentile(value[mask],2) if vmin is None else vmin
    # vmax = np.percentile(value[mask],85) if vmax is None else vmax
    vmin = np.min(value[mask]) if vmin is None else vmin
    vmax = np.max(value[mask]) if vmax is None else vmax
    if vmin != vmax:
        value = (value - vmin) / (vmax - vmin)  # vmin..vmax
    else:
        # Avoid 0-division
        value = value * 0.

    # squeeze last dim if it exists
    # grey out the invalid values

    value[invalid_mask] = np.nan
    cmapper = matplotlib.cm.get_cmap(cmap)
    if value_transform:
        value = value_transform(value)
        # value = value / value.max()
    value = cmapper(value, bytes=True)  # (nxmx4)

    # img = value[:, :, :]
    img = value[...]
    img[invalid_mask] = background_color

    #     return img.transpose((2, 0, 1))
    if gamma_corrected:
        # gamma correction
        img = img / 255
        img = np.power(img, 2.2)
        img = img * 255
        img = img.astype(np.uint8)
    return img

def img_preprocess(image, h, w):
      # Convert the drawn image to grayscale
    img_gray = cv2.cvtColor(image, cv2.COLOR_RGB2GRAY)

    # Threshold the grayscale image to create a binary image
    _, binary_img = cv2.threshold(img_gray, 1, 255, cv2.THRESH_BINARY)

    # Perform flood fill starting from a point inside the shape. Fill the inside with pixel value 0
    seed_point = (int(h/2), int(w/2))
    retval, flooded_image, mask, rect = cv2.floodFill(binary_img, None, seed_point, 0)
    flooded_image = (flooded_image/255).astype(np.uint8)
    return flooded_image

def patch_stiching(flooded_image, h, w, x0, y0): # ((x0, y0) = center of channel,  (w1, h1) = height and width of patch)
    flow_field_updated = np.copy(flow_field)
    flow_field_updated[int(x0-w/2):int(x0+w/2),int(y0-h/2):int(y0+h/2)] = flooded_image


    # flow_field_updated is the main thing that we will use to make our predictions on -
    test_img = np.expand_dims(flow_field_updated, axis = 0)
    test_img = np.expand_dims(test_img, axis = 3) # Shape of test_img = (1, 128, 256)
    return test_img

# Define grid points
x_points = np.linspace(0, 255, 256)
y_points = np.linspace(0, 127, 128)
X, Y = np.meshgrid(x_points, y_points)

def return_quiver_plot(u, v):
    velocity = np.sqrt(u**2 + v**2)
    ax = plt.subplot()
    ax.imshow(velocity, origin = 'lower', extent = (0,256, 0,128), cmap = 'gray')
    q = ax.quiver(X[5::8,5::8], Y[5::8,5::8], u[5::8,5::8], u[5::8,5::8], pivot = 'middle', color = 'red')
    # ax.quiverkey(q, X=0.9, Y=1.05, U=2,
    #             label='m/s', labelpos='E')
    # plt.title("Velocity distribution")
    # plt.show()
    return q

def squeeze_function(img):
  img = np.squeeze(img, axis = 0)
  img = np.squeeze(img, axis = 2)
  return img

# Taking a shape from the user on sketchpad and placing it inside the fluid flow -

h, w = 48, 48 # patch_size in which the obstacle will be drawn
x0, y0 = 64, 128 # (x0, y0) = center of channel

def fill_shape_with_pixels(img): #img is taken by gradio as uint8
    if img is None:
        return np.zeros((h, w), dtype=np.uint8) # "No input sketch"
# Calling the the flooded image function to fill inside the obstacle
    flooded_image = img_preprocess(img, h, w)
# Performing patch statching to put the obstacle at the required center position
    test_img = patch_stiching(flooded_image, h, w, x0, y0)

# Loading and Compiling the Model
    model_path = "Pinns_Loss_file.h5"
    model = load_model(model_path, compile = False)
    model.compile(loss=custom_loss, optimizer=tf.keras.optimizers.AdamW(learning_rate = 0.0001), metrics=['mae', 'cosine_proximity'])

 # Making Model prediction from input sketch shape
    prediction = model.predict(test_img) # (prediction.shape = (1, 128, 256, 3))
    u_pred, v_pred, p_pred = np.split(prediction, 3, axis=3) # shape of u_pred, v_pred, p_pred = (1, 128, 256, 1)

 # De-Normalizing teh Data:
    u_pred = ((u_pred*std_dev_u) + mean_u)
    v_pred = ((v_pred*std_dev_v) + mean_v)
    p_pred = ((p_pred*std_dev_p) + mean_p)

 # Making test_img in shape required by zero_pixel_location
    req_img = squeeze_function(test_img)

# Storing the location of 0 pixel values
    #req_img = req_img.astype(int)
    zero_pixel_locations = np.argwhere(req_img == 0)

# Reducing the dimensions-
    u_profile = u_pred[0][:,:,0]  # shape of u profile to compatible shape (H, W) = (128, 256)
    v_profile = v_pred[0][:,:,0]
    p_profile = p_pred[0][:,:,0]
    p_profile[p_profile>0.02] = 0.02

# Creating a copy of the above profiles-
    u_profile_dash = np.copy(u_profile)
    v_profile_dash = np.copy(v_profile)

# Creating a copy of the above profiles-
    u_profile_dash_1 = np.copy(u_profile)
    v_profile_dash_1 = np.copy(v_profile)


# Hollowing the obstacle out from the u and v plots. Origin of imae is lop left and origin of plot is top right
    for y, x in zero_pixel_locations:
      u_profile_dash[128 - y, x] = 0
      v_profile_dash[128 - y, x] = 0
      # will be used for image
      u_profile_dash_1[y, x] = 0
      v_profile_dash_1[y, x] = 0


# Quiver Plot
    quiver_plot = plt.figure(figsize = (14,6), edgecolor = "gray")
    velocity = np.sqrt(u_profile_dash_1**2 + v_profile_dash_1**2)
    ax = plt.subplot()
    ax.imshow(velocity, cmap = 'gray', extent = (0,256, 0,128))
    q = ax.quiver(X[5::7,5::7], Y[5::7,5::7], u_profile_dash[5::7,5::7], v_profile_dash[5::7,5::7], pivot = 'middle', color = 'red')
    ax.quiverkey(q, X=0.9, Y=1.07, U=2,
                label='m/s', labelpos='E')
    plt.title("Velocity distribution", fontsize = 11)
    plt.xlabel("Length of Channel", fontsize = 11)
    plt.ylabel("Height of Channel", fontsize = 11)

 # StreamLine Plot
    streamline_plot = plt.figure(figsize = (14,6), edgecolor = "gray")
    plt.streamplot(X, Y, u_profile_dash, v_profile_dash, density = 4)
    plt.axis('scaled')
    plt.title("Streamline Plot", fontsize = 11)
    plt.xlabel("Length of Channel", fontsize = 11)
    plt.ylabel("Height of Channel", fontsize = 11)

  # Colorize taken from ZoeDepth Model
    u_colored = colorize(u_profile, cmap = 'jet')
    #cbar_u = plt.colorbar(u_profile,fraction=0.025, pad=0.05)
    v_colored = colorize(v_profile, cmap = 'jet')
    #cbar_v = plt.colorbar(v_colored,fraction=0.025, pad=0.05)
    p_colored = colorize(p_profile, cmap = 'jet')
    #cbar_p = plt.colorbar(p_colored,fraction=0.025, pad=0.05)


    return colorize(req_img, cmap = 'jet'), quiver_plot, streamline_plot, u_colored, v_colored, p_colored

# Importing gr.Blocks()

with gr.Blocks(theme="Taithrah/Minimal") as demo:
  gr.Markdown(
    """
    # Channel Flow - Physics Constrained DNN for Predicting Mean Turbulent Flows
    The App solves 2-D incompressible steady state NS equations for any given 2-D closed geometry. Geometry needs to be drawn around the center of the patch.\n
    It predicts the streamlines,horizontal & vertical velocity profiles and the pressure profiles using a hybrid loss function.\n
    Model Parameters (In SI Units) - Kinematic Viscosity = 0.0001, Input horizontal velocity = 0.075, Input vertical velocity = 0
    """)
  with gr.Row():
    with gr.Column():
      input_sketch = gr.Image(label = "Draw any Obstacle contour around the patch center",
                        tool="sketch", source="canvas", shape=(h, w), brush_radius = 3)
      Process_button = gr.Button("Process Flow Parameters")

    with gr.Column():
      filled_channel = gr.Image(label = "Drawn object within fluid domain of dimensions 128*256", container = True)

  with gr.Row():
    quiver_plot = gr.Plot(label = "Velocity Distribution Around The Obstacle", scale = 2)

  with gr.Row():
    streamline_plot = gr.Plot(label = "Stream Lines Around The Obstacle", scale = 2)

  with gr.Row():
    u_image = gr.Image(label = "Horizontal Velocity")
    v_image = gr.Image(label = "Vertical Velocity")
    p_image = gr.Image(label = "Pressure")


  Process_button.click(fn=fill_shape_with_pixels, inputs=input_sketch, outputs=[filled_channel, quiver_plot, streamline_plot, u_image, v_image, p_image])

demo.launch(debug=True, inline = False)