A quick way to find out whether your digital terrain model file has isolated high points or spikes is to display the terrain model with a color gradient from blue to red as shown in the Global Mapper screenshot below.
In this example, the terrain surface is mostly shaded in blue tones. That is a good indication that there are some elevation spikes somewhere in your terrain model.
![](https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEj-vLEsHGFAhDbZarR7PotbvjdVENr1YWE0cIK7-iW5d2H8hA94fPIqDW-xEDOZCHnwVdNshdcJX2HKw8J0vmOdK0H-2on9a23gNGXf0VvrovRNxDLhF3q4cHlmDGlFt3QdemP7ysIZGA/s400/spike01.png)
A screenshot of a digital terrain model file with no high points is shown below. A good terrain surface is shaded evenly with the colors nicely balanced from blue to red as you go from lower elevations to higher elevations.
![](https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgCpdM-n1EmPlNzstft-gFw0ywsHWPWU5Urfi1EoJMJ-Jvx6wu3pd8ymNRH1womU_gh8oI0Rvxn2Lh2cy6Xy64b6XlCMb_Z5kPxovpYcGtHUx9AGfI-DsodUzKsaHoYevR8tvrvt9f-_g/s400/spike02.png)
![](https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgCpdM-n1EmPlNzstft-gFw0ywsHWPWU5Urfi1EoJMJ-Jvx6wu3pd8ymNRH1womU_gh8oI0Rvxn2Lh2cy6Xy64b6XlCMb_Z5kPxovpYcGtHUx9AGfI-DsodUzKsaHoYevR8tvrvt9f-_g/s400/spike02.png)
This is one way to quickly check your digital elevation models for the presence of isolated elevation spikes.