Struct CogReader 

pub struct CogReader {
    pub metadata: CogMetadata,
    pub overviews: Vec<OverviewMetadata>,
    pub min_usable_overview: Option<usize>,
    /* private fields */
}

COG Reader - efficient COG access with range requests

Fields

metadata: CogMetadata

overviews: Vec<OverviewMetadata>

Overview levels (sorted by scale factor, smallest to largest)

min_usable_overview: Option<usize>

Minimum usable overview index - overviews beyond this have insufficient data None means all overviews are usable, Some(n) means only overviews 0..n are usable

Implementations

impl CogReader

pub fn open(source: &str) -> AnyResult<Self>

Open a COG from any source (local file, HTTP URL, or S3)

pub fn from_reader(reader: Arc<dyn RangeReader>) -> AnyResult<Self>

Open from an existing range reader

pub fn best_overview_for_resolution( &self, extent_src_width: usize, extent_src_height: usize, ) -> Option<usize>

Find the best overview level for a given source extent size

Parameters:

• extent_src_width: How many source pixels the extent covers at full resolution
• extent_src_height: How many source pixels the extent covers at full resolution
• output_width: How many pixels we’re actually rendering (e.g., 256)
• output_height: How many pixels we’re actually rendering (e.g., 256)

Returns None if full resolution should be used

pub fn read_overview_tile( &self, overview_idx: usize, tile_index: usize, ) -> AnyResult<Vec<f32>>

Read a tile from a specific overview level

pub fn read_tile(&self, tile_index: usize) -> AnyResult<Vec<f32>>

Read a single tile’s raw data and decompress

pub fn sample(&self, band: usize, x: usize, y: usize) -> AnyResult<Option<f32>>

Sample a single pixel value

pub fn estimate_min_max(&self) -> AnyResult<(f32, f32)>

Estimate min/max from sampling (when GDAL stats not available)

For local files: Scans ALL tiles for accurate min/max values For remote files (S3/HTTP): Samples a few tiles for efficiency

Use estimate_min_max_fast() to always use fast sampling regardless of source.

pub fn estimate_min_max_fast(&self) -> AnyResult<(f32, f32)>

Fast min/max estimation - samples only corner and center tiles Use this for remote files where full scans are expensive