FS2004 calculating inf destination coordinates

[kjjj11223344]

I am adapting my port of Ortho4XP to FS2004 (https://github.com/stackTom/Ortho4XP_FSX_P3D). I can't seem to figure out how to calculate the appropriate coordinates for the destination to fit within each LOD 13 terrain cell. The SDK says that "Each terrain cell falls on a multiple of 360/32768 degrees latitude, which is 0.010986328125 decimal degrees and 480/32768 degrees longitude, which is 0.0146484375 decimal degrees."

So, I do this:
new latitude = Floor(latitude / 0.010986328125)* 0.010986328125
new longitude = Floor(longitude / 0.0146484375) * 0.0146484375

if latitude or longitude are positive and do this, if negative:

new longitude = Ceiling(latitude / 0.010986328125)* 0.010986328125
new longitude = Ceiling(longitude / 0.0146484375) * 0.0146484375

I do this to fit the scenery onto the LOD 13 cell bounds...

For example, assume north latitude is 51.17934297928926, south latitude is 50.958426723359935, west longitude is -0.3515625, and east longitude is 0.0. We get:
new north latitude = Floor(51.17934297928926 / 0.010986328125) * 0.010986328125 = 51.17431640625
new south latitude = Floor(50.958426723359935 / 0.010986328125) * 0.010986328125 = 50.95458984375
new west longitude = Ceiling(-0.3515625 / 0.0146484375) * 0.0146484375 = -0.3515625
new east longitude = Floor(0.0 / 0.0146484375) * 0.0146484375 = 0.0

Nevertheless, I get the infamous rim of water around the scenery. What I am doing wrong. I think I am interpreting the SDK incorrectly, but can't figure out what I'm doing wrong.

[Source]
Type = MultiSource
NumberOfSources = 6

[Source1]
Season          = Summer
Variation          = January,February,March,April,May,June,July,August,September,October,November,December
Type          = Custom
Layer          = Imagery
SourceDir  = G:\Ortho4XP_FSX_P3D\Orthophotos\+50-010\+51-001\GO2_14
SourceFile = 5472_8176_GO214.tga
Lon               = -0.3515625
Lat               = 51.17934297928926
NumOfCellsPerLine = 4096       ;Pixel isn't FSX/P3D
NumOfLines        = 4096       ;Pixel isn't used in FSX/P3D
CellXdimensionDeg = 8.58306884765625e-05
CellYdimensionDeg = 5.3934632795245296e-05
PixelIsPoint      = 0
SamplingMethod    = Point
NullValue         = 255,255,255

[Source2]
Season          = Spring
Variation          = January
Type          = Custom
Layer          = Imagery
SourceDir  = G:\Ortho4XP_FSX_P3D\Orthophotos\+50-010\+51-001\GO2_14
SourceFile = 5472_8176_GO214.tga
Lon               = -0.3515625
Lat               = 51.17934297928926
NumOfCellsPerLine = 4096       ;Pixel isn't FSX/P3D
NumOfLines        = 4096       ;Pixel isn't used in FSX/P3D
CellXdimensionDeg = 8.58306884765625e-05
CellYdimensionDeg = 5.3934632795245296e-05
PixelIsPoint      = 0
SamplingMethod    = Point
NullValue         = 255,255,255

[Source3]
Season          = Fall
Variation          = January
Type          = Custom
Layer          = Imagery
SourceDir  = G:\Ortho4XP_FSX_P3D\Orthophotos\+50-010\+51-001\GO2_14
SourceFile = 5472_8176_GO214.tga
Lon               = -0.3515625
Lat               = 51.17934297928926
NumOfCellsPerLine = 4096       ;Pixel isn't FSX/P3D
NumOfLines        = 4096       ;Pixel isn't used in FSX/P3D
CellXdimensionDeg = 8.58306884765625e-05
CellYdimensionDeg = 5.3934632795245296e-05
PixelIsPoint      = 0
SamplingMethod    = Point
NullValue         = 255,255,255

[Source4]
Season          = Winter
Variation          = January
Type          = Custom
Layer          = Imagery
SourceDir  = G:\Ortho4XP_FSX_P3D\Orthophotos\+50-010\+51-001\GO2_14
SourceFile = 5472_8176_GO214.tga
Lon               = -0.3515625
Lat               = 51.17934297928926
NumOfCellsPerLine = 4096       ;Pixel isn't FSX/P3D
NumOfLines        = 4096       ;Pixel isn't used in FSX/P3D
CellXdimensionDeg = 8.58306884765625e-05
CellYdimensionDeg = 5.3934632795245296e-05
PixelIsPoint      = 0
SamplingMethod    = Point
NullValue         = 255,255,255

[Source5]
Season          = HardWinter
Variation          = January
Type          = Custom
Layer          = Imagery
SourceDir  = G:\Ortho4XP_FSX_P3D\Orthophotos\+50-010\+51-001\GO2_14
SourceFile = 5472_8176_GO214.tga
Lon               = -0.3515625
Lat               = 51.17934297928926
NumOfCellsPerLine = 4096       ;Pixel isn't FSX/P3D
NumOfLines        = 4096       ;Pixel isn't used in FSX/P3D
CellXdimensionDeg = 8.58306884765625e-05
CellYdimensionDeg = 5.3934632795245296e-05
PixelIsPoint      = 0
SamplingMethod    = Point
NullValue         = 255,255,255

[Source6]
Season          = LightMap
Variation          = LightMap
Type          = Custom
Layer          = Imagery
SourceDir  = G:\Ortho4XP_FSX_P3D\Orthophotos\+50-010\+51-001\GO2_14
SourceFile = 5472_8176_GO214_night.tga
Lon               = -0.3515625
Lat               = 51.17934297928926
NumOfCellsPerLine = 4096       ;Pixel isn't FSX/P3D
NumOfLines        = 4096       ;Pixel isn't used in FSX/P3D
CellXdimensionDeg = 8.58306884765625e-05
CellYdimensionDeg = 5.3934632795245296e-05
PixelIsPoint      = 0
SamplingMethod    = Point
NullValue         = 255,255,255

[Destination]
DestDir             = G:\Ortho4XP_FSX_P3D\Orthophotos\+50-010\+51-001\GO2_14\ADDON_SCENERY\scenery
DestBaseFileName     = 5472_8176_GO214
BuildSeasons        = 1
UseSourceDimensions  = 0
CompressionQuality   = 100
NorthLat             = 51.17431640625
SouthLat             = 50.95458984375
WestLon             = -0.3515625
EastLon             = 0.0
LOD = 13

Do images have to be in a 3:4 aspect ratio? This is how the example in the SDK is. Furthermore 0.010986328125 / 0.0146484375 = 3/4 as well...

 

[kjjj11223344]

I know there is a tool called photocalc to calculate this, but I can't find a link to it. Also, I rather know how to do it so I can add it to my code.