# 4. Invert for distance calculation (Scipy treats '0' as foreground) # If your shape is white (1), invert it so shape is 0. shape = 1 - binary
Try converting a simple circle PNG. Then zoom in 400% on both the original and the SDF. You will never look at raster images the same way again. Have a specific use case? Let me know in the comments if you need help with MSDFs or 3D volume generation from 2D SDFs.
# 2. Normalize to binary (0 or 255) _, binary = cv2.threshold(img, 127, 255, cv2.THRESH_BINARY)
Is your shape black on white or white on black? SDFs care about sign . If your output looks like a bump instead of a cavity, invert the image before processing. convert png to sdf
Enter the .
# 3. Convert to float range [0, 1] binary = binary / 255.0
import cv2 import numpy as np from scipy import ndimage def png_to_sdf(input_path, output_path, radius=15): # 1. Load PNG as Grayscale img = cv2.imread(input_path, cv2.IMREAD_GRAYSCALE) Then zoom in 400% on both the original and the SDF
# 6. Normalize SDF to 0-255 range for storage sdf_normalized = (dt / dt.max()) * 255 sdf_normalized = sdf_normalized.astype(np.uint8)
Raster images are great for humans looking at a screen. But for machines—especially those navigating a 3D space or rendering crisp fonts—they are notoriously inefficient.
// Inside your fragment shader float distance = texture(sdfTexture, uv).r; float finalAlpha = smoothstep(0.5 - 0.05, 0.5 + 0.05, distance); gl_FragColor = vec4(1.0, 1.0, 1.0, finalAlpha); Because you are reading a distance rather than a color , you can zoom in 10,000% and the edge will remain mathematically perfect. Converting a PNG to an SDF transforms a static bitmap into a dynamic mathematical field. Whether you are rendering fonts in Unreal Engine, generating 3D meshes for simulation, or just trying to get a crisp icon on a WebGL canvas, the conversion is worth the five minutes it takes to set up. Let me know in the comments if you
Standard SDFs struggle with sharp corners (like the tip of a star). If you need perfect vector quality, look into MSDF (Multi-channel SDF). Converting PNG to MSDF requires specialized tools like msdfgen . The Result: Perfect Scaling Once converted, you can render your SDF in a shader like this (GLSL snippet):
# 5. Calculate Euclidean Distance Transform # dt = Distance to nearest 0 (edge) dt = ndimage.distance_transform_edt(shape)