Ordnance Survey DTM - how to colour

create R,G,B with expressions.

 

I make These Parameters, so i can choose a color.

 

Then i create a expressioon that uses height.

 

Depening on speed of colour increase u can use linear, cubic etc. algorithms.

 

U also need to normalize them ( for instance fme_c0lor is between 0 and 1 float)

 

 

Here is an example:

 

 

 

 

The GS_Function attribute holds the output for a algorithm. I create a couple algorithms and put them in a userchoicelist. R,G,B are also parameter, so u can use the wheel to choose a startingcolor.

 

 

It creates the sunnysky in this pic.

 

 

I use a RasterBandInterpretationCoercer to coerce it to UNIT8, scaling by by data values, use the AttributeCreator to create a palette and then The RasterPaletteAdder to add the palette to the raster, then the RasterPaletteResolver to turn it into an RGB raster

 

 

The palette i use for elevation is below.  The zero value entry is a special case I use for NoData

RGB24

 

0 0,0,0

 

1 118,219,211

 

2 125,220,210

 

3 129,221,210

 

4 132,222,209

 

5 136,223,209

 

6 140,224,209

 

7 143,225,208

 

8 147,226,208

 

9 151,227,208

 

10 155,228,207

 

11 158,229,207

 

12 162,230,207

 

13 166,231,206

 

14 169,232,206

 

15 173,233,206

 

16 177,234,205

 

17 180,235,205

 

18 184,236,205

 

19 188,237,204

 

20 192,238,204

 

21 195,239,204

 

22 199,240,203

 

23 203,241,203

 

24 206,242,203

 

25 210,243,202

 

26 214,244,202

 

27 217,245,202

 

28 221,246,201

 

29 225,247,201

 

30 229,248,201

 

31 232,249,200

 

32 236,250,200

 

33 240,251,200

 

34 243,252,199

 

35 247,253,199

 

36 251,254,199

 

37 255,255,199

 

38 255,255,197

 

39 255,255,195

 

40 255,255,193

 

41 255,255,191

 

42 255,255,189

 

43 255,255,187

 

44 255,255,185

 

45 255,255,183

 

46 255,255,181

 

47 255,255,179

 

48 255,255,177

 

49 255,255,175

 

50 255,255,174

 

51 255,255,172

 

52 255,255,170

 

53 255,255,168

 

54 255,255,166

 

55 255,255,164

 

56 255,255,162

 

57 255,255,160

 

58 255,255,158

 

59 255,255,156

 

60 255,255,154

 

61 255,255,152

 

62 255,255,151

 

63 255,255,149

 

64 255,255,147

 

65 255,255,145

 

66 255,255,143

 

67 255,255,141

 

68 255,255,139

 

69 255,255,137

 

70 255,255,135

 

71 255,255,133

 

72 255,255,131

 

73 255,255,129

 

74 255,255,128

 

75 253,253,127

 

76 252,251,127

 

77 251,250,127

 

78 250,248,127

 

79 249,246,127

 

80 248,245,126

 

81 247,243,126

 

82 246,241,126

 

83 245,240,126

 

84 244,238,126

 

85 243,236,125

 

86 242,235,125

 

87 241,233,125

 

88 240,231,125

 

89 239,230,125

 

90 238,228,124

 

91 237,226,124

 

92 236,225,124

 

93 235,223,124

 

94 234,222,124

 

95 233,220,124

 

96 232,218,123

 

97 231,217,123

 

98 230,215,123

 

99 229,213,123

 

100 228,212,123

 

101 227,210,122

 

102 226,208,122

 

103 225,207,122

 

104 224,205,122

 

105 223,203,122

 

106 222,202,121

 

107 221,200,121

 

108 220,198,121

 

109 219,197,121

 

110 218,195,121

 

111 217,194,121

 

112 214,191,118

 

113 212,188,116

 

114 210,186,114

 

115 208,183,112

 

116 205,180,109

 

117 203,178,107

 

118 201,175,105

 

119 199,172,103

 

120 197,170,100

 

121 194,167,98

 

122 192,164,96

 

123 190,162,94

 

124 188,159,91

 

125 185,156,89

 

126 183,154,87

 

127 181,151,85

 

128 179,148,82

 

129 177,146,80

 

130 174,143,78

 

131 172,141,76

 

132 170,138,73

 

133 168,135,71

 

134 166,133,69

 

135 163,130,67

 

136 161,127,64

 

137 159,125,62

 

138 157,122,60

 

139 154,119,58

 

140 152,117,55

 

141 150,114,53

 

142 148,111,51

 

143 146,109,49

 

144 143,106,46

 

145 141,103,44

 

146 139,101,42

 

147 137,98,40

 

148 135,96,38

 

149 135,97,41

 

150 135,98,45

 

151 136,100,49

 

152 136,101,53

 

153 137,103,57

 

154 137,104,61

 

155 137,106,65

 

156 138,107,68

 

157 138,109,72

 

158 139,110,76

 

159 139,112,80

 

160 139,113,84

 

161 140,114,88

 

162 140,116,92

 

163 141,117,95

 

164 141,119,99

 

165 141,120,103

 

166 142,122,107

 

167 142,123,111

 

168 143,125,115

 

169 143,126,119

 

170 143,128,123

 

171 144,129,126

 

172 144,131,130

 

173 145,132,134

 

174 145,133,138

 

175 145,135,142

 

176 146,136,146

 

177 146,138,150

 

178 147,139,153

 

179 147,141,157

 

180 147,142,161

 

181 148,144,165

 

182 148,145,169

 

183 149,147,173

 

184 149,148,177

 

185 150,150,181

 

186 150,150,181

 

187 151,150,181

 

188 152,150,181

 

189 153,150,181

 

190 154,150,181

 

191 155,150,181

 

192 155,150,181

 

193 156,150,181

 

194 157,150,181

 

195 158,150,181

 

196 159,150,181

 

197 160,150,181

 

198 160,150,181

 

199 161,150,181

 

200 162,150,181

 

201 163,150,181

 

202 164,150,181

 

203 165,150,181

 

204 165,150,181

 

205 166,150,181

 

206 167,150,181

 

207 168,150,181

 

208 169,150,181

 

209 170,150,181

 

210 170,150,181

 

211 171,150,181

 

212 172,150,181

 

213 173,150,181

 

214 174,150,181

 

215 175,150,181

 

216 175,150,181

 

217 176,150,181

 

218 177,150,181

 

219 178,150,181

 

220 179,150,181

 

221 180,150,181

 

222 181,150,181

 

223 183,153,183

 

224 185,156,185

 

225 187,159,187

 

226 189,162,189

 

227 192,165,192

 

228 194,169,194

 

229 196,172,196

 

230 198,175,198

 

231 201,178,201

 

232 203,181,203

 

233 205,185,205

 

234 207,188,207

 

235 210,191,210

 

236 212,194,212

 

237 214,197,214

 

238 216,200,216

 

239 219,204,219

 

240 221,207,221

 

241 223,210,223

 

242 225,213,225

 

243 228,216,228

 

244 230,220,230

 

245 232,223,232

 

246 234,226,234

 

247 237,229,237

 

248 239,232,239

 

249 241,235,241

 

250 243,239,243

 

251 246,242,246

 

252 248,245,248

 

253 250,248,250

 

254 252,251,252

 

255 255,255,255