DEM data sources.txt ---------------- TerrainBase/ETOPO5, from the NOAA National Data Center/NGDC (18 MB uncompressed) http://www.ngdc.noaa.gov/seg/fliers/se-1104.shtml TerrainBase Global 5-min DTM Ver 1.0 (NGDC). little_endian. 2160 rows x 4320 columns The file may be thought of as having a logical record size of 8640 bytes. The data start at the North Pole (90 deg N, 0 deg 0' E) and are arranged in bands of 360 degrees x 12 points/degree = 4320 values (8640 bytes) ranging eastward from 0 deg 0' East longitude to 359 deg 55' East longitude (since it represents the North Pole, all possible longitudes still refer to a single point, thus the first band has 4320 identical values of -4290 m). The 8641st starts the latitude band for 89 deg 55' N, and so on. There is NO record for the South Pole (elevation 2810 m.) ETOPO2, Smith, W. H. F. and D. T. Sandwell, NOAA/NGDC (133 MB uncompressed) http://topex.ucsd.edu/marine_topo/mar_topo.html http://www.ngdc.noaa.gov/mgg/fliers/01mgg04.html 2-minute (latitude-longitude) resolution 1 minute of latitude = 1 nautical mile, or 1.852 km). (8)1350 x (4)1350 =10800 x 5400 A 6336 by 10800 grid of 2-byte integers = 136,857,600 bytes(16-bit signed integer ). Byte order is big_endian. The Mercator projected image spans longitudes from 0 E to 360 E and latitudes from 72.006 N to -72.006 N. "ETOPO2.dos" is in little-endian format for Intel (PC) and DEC (Vax) computers. The data are cell-centered, with an array size of 10800 columns x 5400 rows; coverage is from 180° West to 179° 58' East and 90° North to 89° 58' South. A data record for the South Pole is not in these files -- assume 2810m as the elevation. GTOPO30 are regularly spaced at 30-arc seconds (approximately 1 kilometer). 33 smaller pieces, or tiles. Total size = 21,600 rows and 43,200 columns. Motorola byte order (most significant byte first) The global 16-bit DEM (21,600 rows by 43,200 columns) has a size of 1.74 gigabytes. GTOPO30 is a global data set covering the full extent of latitude from 90 degrees south to 90 degrees north, and the full extent of longitude from 180 degrees west to 180 degrees east. The horizontal grid spacing is 30-arc seconds (0.008333333333333 degrees), resulting in a DEM having dimensions of 21,600 rows and 43,200 columns. The horizontal coordinate system is decimal degrees of latitude and longitude referenced to WGS84. The vertical units represent elevation in meters above mean sea level. The elevation values range from -407 to 8,752 meters. In the DEM, ocean areas have been masked as "no data" and have been assigned a value of -9999. GLOBE, "Global Land One-km Base Elevation" project (287 MB, expands to 1.7GB). http://www.ngdc.noaa.gov/seg/topo/globe.shtml Bathymetry is not included in GLOBE Version 1.0. (See NGDC's TerrainBase or ETOPO5 for lower-resolution bathymetric data. GLOBE Version 2.0 may include bathymetric data.) Every tile contains values of -500 for oceans 21600 rows x 43200 columns little-endian (Intel) byte order. Datum WGS84 NIMA Level 0 elevation post spacing is 30 arc second (nominally one kilometer). Maui_1k, BT file from the "Virtual Terrain Project" (4MB uncompressed) http://www.vterrain.org http://www.vterrain.org/BT/index.html USGS 1/250,000 DEMs: Map size not dem Rez 7.5-minute, : 10 or 30 meter 15-minute, 2-arc-second (also known as 30-minute), and 1-degree units. The 7.5- and 15-minute DEMs are included in the large scale category while 2-arc-second DEMs fall within the intermediate scale category and 1-degree DEMs fall within the small scale category - (Source: USGS) 7.5-minute (1:24,000-scale) DEMs; 7.5-minute tiles; resolution: 30 meters; some at 10 meters. 15-minute (1:63,360-scale) DEMs; 15-minute tiles; resolution: 2 by 3 arc seconds (approximately 60 meters); coverage: Alaska 1-degree (1:250,000-scale) DEMs; 1-degree tiles; resolution: 3 arc seconds (approximately 90 meters) 250k: http://edc.usgs.gov/glis/hyper/guide/1_dgr_demfig/states.html 24k: http://gisdatadepot.com/dem sdts2dem to convert 24k sdts files to a dem file for import by DTM. 250k dems imported by DTM SRTM demo dems:The NIMA-MOU stipulates that full resolution (1-arc-second) terrain and radar image data over the United States will be releasable without restrictions to all users. For non -U.S. areas, reduced resolution (3-arc-second) terrain data will be fully releasable without restrictions. Motorola 16-bit signed integer SRTM-3 files contain 1201 lines and 1201 samples (1 point overlap){90 Meters} SRTM-1 files contain 3601 lines and 3601 samples ("")){30 Meters} National Elevation Dataset (NED) NED: NED has a resolution of one arc-second (approximately 30 meters). The NED will be delivered in the Spatial Data Transfer Standard (SDTS) raster profile. demo dems: BIL format in Motorola bytes.16-bit signed integer 1201x1201 (3-arc-second) ArcGrid or Surfer .grd XYZ ascii TIN : import as mesh Shape file fan or strip.. as mesh Mars / planeteary dems Fractal dems ... input X,Y size and type of data: Shortint, Integer, Float, Double 10 Meter (360x180x64= 4147200 cells x ~10meg = ?41 terra ; x~3meg = 12.4T) 3456000 x 1728000 = 5,971,968,000,000 points [24k 10M dems] 30 Meter: 1 Arc Second (= 4147200x ~1meg = ?4 terra) [24k 30M dems] 1AS SRTM 1 degree cells 3601x3601= ~25 meg each 90 Meter: 3 AS (360x180x ~10meg = 648 gig x~3meg= 194G) [250k dems] {120(1) x 120(1) per degree = 432000 x 216000} {The above are wrong as land only covers ~30 percent and the poles make cells smaller; conversion from Ascii to binary = ~10 to ~3 meg files} 1000 M: 30 AS [43,200 columns x 21,600 rows] (1.7G) [Globe] 1852 M: 1 minute of latitude = 1 nautical mile, or 1.852 km [NA] 3704 M: 2-minute (latitude-longitude) resolution [10800 columns x 5400 rows] ~10000 M: 5 Minute [4320 columns x 2160 rows] (18meg) [Etopo] Maps >68 degrees 15x36' 62..68 15x30' 59..62 15x22.5' >59 15x20' 1 degree Dems > 70 degrees every 9" = 401 points (all are 1201 vertically) 50..70 6" = 601 -50..50 3" = 1201x1201 points Tree of DEM 5', 30AS, 3AS, 10M Datum Differences : WGS84... Cell Centroid: Offset to Zero Given location: (360 x 180 degrees = 64800 1* cells (x64 24k cells= 4147200 cells)) If 24k else If 1* else If Global else Etopo: then display TYPES of DISPLAY Elevation Tint Slope tint Hydro Basins: Stream - flow - Valleys Contours LOS: Point A to B, A Circled, Profile A to B GL TIN- Roam Rotating Globe <-> Projected global map displays (Mercator, Robinson, etc.) Overlay Point, Line, Area .shp files (2D & 3D) Use Patterns for Areal fill (multiple objects or texture bitmap) Objects for Points and Lines (Trees for fill...) 3D Geology (depth) Movement <> Temporal history Processes (Flood, Route, Areal selection, Boolean - Solid +,-,both Dem to tpcfg loader Dem LR coord id <> Gtopo UL coords id map location LR Coords: Map ID- Map name - 4 corners determine bounds Need ID to determine map - Coords are double: hard to check 'actual' location...round to integers Need Box of data required to make grid array Resize selected area (Add maps together)(Crop off boundary) Rescale Trim % of Rows-Columns Image of area-> Full cropped area, Rescaled full area Display types Overlay Adjustment of Datum Fit / Center Cell Processing dems to HTF Get dems Unpack from .gz Rename Extensions to .dem Zip original dems (for posterity) Delete .gzs Convert dems to bins convert bins to HTF Zip conversions (bins) Delete dems Image TEXTURES <> World is ~ Meters around ?Weather images 10K pixels AVHRR Global Imagery ~ 1K pixels ~200 Meg? Landsat 1..3 Path / Row 90M pixels Landsat 4..7 Path / Row 30M pixels NHAP photos ~ 10M Pixels HiRes satellites ~ 1 Meter Pixels A 3D Map comprised of layers of information. Tiles of data enable moving from 1 area to another while reducing the amount of data required to be held in memory. Layers: Base layer of elevation data in 5', 30AS, 3AS, (30)10 meter file formats. (cell size) Prepare by doing a Search of disks for Dems.. process into Htf files. The texture defaults to a color-range from blue to orange based on Terrain elevations. Imagery of the area. If not at the same scale, then scaled to fit the elevation layer. (Registered/rectified) Shape files may contain polygons representing "ground cover", transportation (roads-railways), hydrology, etc. Shape files may be translated into "flat" texture or be represented by 3D objects: Vegetation, roads with embankments-guard rails, flowing rivers w/waves, canal-locks, river banks, telephone poles with wires, ... Transform 2D into 3D .shp files. . Edit files as a 2D overlay on a DEM. . Get elevation for shape point locations . Save file as a 3D file . Convert Dem into .shp file fans? . Dem into a TIN w/shape file fan import . (added resolution to the grid data) Entrance to a tile would require flags that data was available and from the data available which "texture" was applied, and from there the representation of the layers of shape files. A shape file may contain 2D or 3D polygons, lines, points; 3d fans-or-strips; however, only 1 type of shape pertaining to 1 type of object it represents per file. (1 layer each for vegetation, roads, railways, structures,... ) An area tiles : 1 Elevation, 0..1 Image, 0..1..n layers of shape files. gee to further complicate things the shape files might cover many tiles of elevation-image. There might be various "scales" of elevation-images covering the same area. Selection of the Scale would determine which of the available layers was actually accessed... Zooming in would change the elevation-image tile selection while the shape coverage might remain the same. Actually to get real complicated the selection could determine nothing and the availability of the data would determine what was used, even mixing elevation-image-shape coverage from different "suggested" scale ranges. (a representation of availability could be a 3x3 of "led's". the center is always where you are, Green is >1 scale range, yellow is 1, red is no data available.) Selection of objects representing the shape file data could range from basic geometric shapes (default-minimum) to high polygon models. Legend selection of a file per object type-layer to actual files per each object in that layer. The Roam-distance-movement-speed could be used to select from a shape to a shape/w/texture (decals..imposters) to a low-rez model to a high-rez model to a fully detailed high resolution model. Besides placing 3D objects upon the terrain the shape file objects would also have to be linked to a database so their attributes could be displayed (pop up window or a status bar), used in analysis of the ?scenario? physical geographical relationships, or determine the actual representation of the object in a changing time aware scenario. Annotation of objects would not be a default capability, although it could be accomplished... with another layer. A 360x180 array (64800) x4 'layers' =259200 Layers: Topo, Photo, Shape, Data Type Each array 'degree' has 4 bytes coded: Each byte has 8 bits On/Off : Available REZ: [1] [2] [3] [4] 300AS Topo 10,000M Weather Global Data 30AS Globe 1,000M AVHRR Scale 3AS Dems 90M MSS ? {Latitude changes density... data points per} ? 1AS .... 30M TM ? {because it is there and Landsat fits it?} 0.3AS .... 10M TM+ ? 0.03AS .... 1M ? ? 0.003AS .... .1M ? ? 0.0003AS .... 0.01M ? ? Data Type: Geology, Complete coverage Interior data, Interior Photo, Interior Panoramic Photo, Exterior Photo, Exterior Panoramic Photo, Metadata.. Sundry information ..Computed-Interpolated/Measured Accuracy ============================================================== Ideas for to do Stuff Load Files md2, HL, obj, 3DS,... MSE Export to POV, VRML 1&2, VDO, X Romka Tutor: DXF Terragen Terrain file specification, DEM,Fractals... a Glscene format: ascii header and a .bin file of data Elevation/Image/Object placement DEM base; Utilities Tiler, Various 'Roam types' Texture/Image Overlay Building/Object Placement Actor Movement Actor -bone/flesh/skin editing Morphing Animal Generation Route-Behavior-physics: Object movement Car-Plane-Train.. floods, volcanic flow, tornado Portal - Maze Generator.. Black box- press 'button' and a door opens.. use as a passage through a 'wall'... regen maze when out of this tile Keyboard - Mouse - Joystick control (Object selection for editing/Morph/ Link to attributes) (warping <> Morph sticky-stay there, linear pull) bmpfont <> Fonts (Nehe outline & 3D fonts; Delphi3D text3d.zip) Fireworks -type selection/Placement/Duration-Direction / Timeline-Script / Sound fireworks, particles, metaballs... Planet Rotation/Generation(fractal)