Class GridDisplayScale

Namespace

EncDotNet.S100.Pipelines.Coverage

Assembly

EncDotNet.S100.Core.dll

Derives a gridded coverage's minimum display scale (the scale beyond which it is hidden as you zoom out) from its grid spacing, for datasets that declare none.

public static class GridDisplayScale

Inheritance

object

GridDisplayScale

Inherited Members

object.Equals(object)

object.Equals(object, object)

object.GetHashCode()

object.GetType()

object.MemberwiseClone()

object.ReferenceEquals(object, object)

object.ToString()

Remarks

A grid drawn with many nodes behind each screen pixel shows nothing the mariner can read, yet every such dataset still costs a raster draw per frame; hundreds of them made zoomed-out panning lag. The cutoff is where one nominal screen pixel (0.28 mm, as for S-101 display scales) covers NodesPerPixel grid nodes. A display scale the dataset or its catalogue declares takes precedence.

Fields

MetresPerDegreeLatitude

Metres per degree of latitude (mean).

public const double MetresPerDegreeLatitude = 111320

Field Value

double

NodesPerPixel

Grid nodes behind one screen pixel at the cutoff.

public const double NodesPerPixel = 4

Field Value

double

PixelSizeMetres

Nominal screen pixel pitch in metres (0.28 mm).

public const double PixelSizeMetres = 0.00028

Field Value

double

Methods

FromGrid(GridMetadata, bool)

The minimum display scale denominator for grid, using its finer axis spacing. A geographic grid's spacing is in degrees (latitude spacing converts directly; longitude spacing shrinks with latitude, so the latitude axis alone decides); a projected grid's is in metres.

public static int? FromGrid(GridMetadata grid, bool geographic)

Parameters

grid GridMetadata

The full-resolution grid.

geographic bool

True when the grid's CRS is geographic (degrees).

Returns

int?

FromSpacing(double)

The minimum display scale denominator for a grid whose node spacing is spacingMetres, or null when the spacing is not a positive finite number.

public static int? FromSpacing(double spacingMetres)

Parameters

spacingMetres double

The grid's finest node spacing, in metres.

Returns

int?